ABSTRACT PACHECO DOMINGUEZ, WILMER JAVIER. Effect ...

ABSTRACT

PACHECO DOMINGUEZ, WILMER JAVIER. Effect of Particle Size and Inclusion Level

of DDGS, and Pellet Quality on Nutrient Digestibility, Gastrointestinal Development, and

Live Performance of Broilers and Swine. (Under the direction of Drs. John Brake and Peter

Ferket).

Distillers dried grains with solubles (DDGS) is the co-product that remains after

fermenting the starch fraction of grains to produce ethanol. Previous research studies have

shown that the main limitations for using DDGS in poultry and swine diets were reduced

pellet quality and increased nutrient variability. Our working hypothesis was that further

grinding of DDGS would improve pellet quality and live performance in poultry and swine

and that the optimum dietary inclusion would depend upon feed formulation strategies. The

first study (Chapter 2) was designed to evaluate the effect of inclusion level and particle size

of DDGS as well as soybean meal (SBM) particle size on pellet durability index (PDI). Diets

containing DDGS exhibited improved (P≤0.05) PDI relative to diets without DDGS. Further

grinding of SBM in diets with DDGS also improved (P≤0.05) PDI. Adding 30% DDGS to

corn-soy diets improved PDI and further grinding of SBM, but not DDGS, improved pellet

quality.

The second study (Chapter 3) evaluated the effect of particle size and DDGS

inclusion on pellet quality and live performance of broilers fed diets formulated on a

digestible amino acid (AA) basis. Birds fed diets with fine DDGS consumed more feed

(P≤0.05) and exhibited greater BW (P≤0.05) at 42 d than birds fed diets with coarse DDGS

with no difference in feed efficiency. Birds fed pelleted diets with fines removed exhibited

greater BW at 35 and 42 d than birds fed pelleted diets with 50% fines. Birds fed diets

containing 30% DDGS consumed more feed (P≤0.05) but exhibited poorer feed efficiency

(P≤0.05) at 42 d than birds fed 15% DDGS with no differences in BW. The results observed

on this experiment demonstrated that broilers exhibited improved live performance when fed

finely ground DDGS (482 µm) with no fines in the feed and that up to 30% DDGS could be

fed when diets were formulated on a digestible AA basis.

The third study (Chapter 4) evaluated the effect of dietary DDGS inclusion and the

method of crude fat analysis on pellet quality, nutrient digestibility, incidence of footpad

lesions, and broiler live performance in diets formulated on a total AA basis. Increasing

dietary inclusion of DDGS to 30% reduced pellet quality, BW, and protein digestibility as

well as increased footpad lesions. Feed efficiency was also poorer. Evidently, broilers can be

fed up to 15% DDGS in diets formulated on total AA basis while the method of estimating

crude fat had a marginal effect on live performance.

The final experiment (Chapter 5) evaluated the effect of DDGS particle size and

percentage fines on grower-finisher pig performance. Particle size of DDGS and percentage

fines in the feed did not impact (P≥0.05) daily gain, daily feed intake, or feed efficiency. It

was determined that the particle size of DDGS did not improve overall live performance so

DDGS did not need to be further ground upon receipt at the feed mill. In addition, up to 25%

pellet fines could be fed without affecting grower-finisher pig performance.

Based on the results of these 4 studies, it was concluded that: (1) further grinding

DDGS did not influence pellet quality and grower-finisher pig live performance; (2) grinding

SBM improved pellet quality; (3) feed containing up to 25% fines could be fed to broilers or

grower-finisher pigs without adverse effects on live performance; (4) and use of digestible

AA values during feed formulation allowed for higher DDGS inclusion.

Effect of Particle Size, DDGS Inclusion, and Pellet Quality on Nutrient Digestibility,

Gastrointestinal Development, and Live Performance of Broilers and Swine

by

Wilmer Javier Pacheco Dominguez

A dissertation submitted to the Graduate Faculty of

North Carolina State University

in partial fulfillment of the

requirements for the Degree of

Doctor of Philosophy

Physiology and Nutrition

Raleigh, North Carolina

2014

APPROVED BY:

_______________________________ ______________________________

John T. Brake, Ph.D. Peter R. Ferket, Ph.D.

Co-chair Co-chair

________________________________ ________________________________

Charles R. Stark, Ph.D. Vernon Felts, Ph.D.

________________________________

Mark Knauer, Ph.D.

ii

DEDICATION

To

God who strengthens me in times of weakness

My dear family; my mother Juana (QDDG), my father Virgilio, my brothers; Johnny, Hector,

Jorge, Rodolfo, Virgilio, Rodilio, Antonio (QDDG),

and my sisters; Lina (QDDG), and Lessy.

My beloved girlfriend Indira Medina.

All my friends who made this journey an enjoyable one.

“I am because of you”

iii

BIOGRAPHY

Wilmer J. Pacheco was born in Las Vegas, Santa Barbara, Honduras, on June 9th

,

1983. He spent the first years of his life studying in this small town in the mountains of

Honduras. During his childhood he collaborated in the farm activities helping his father to

grow corn and beans. After elementary school, he moved to San Pedro Sula where he studied

in the Honduran-German Technical Center where he learned the general concepts of

maintenance of industrial machines. In 2002, he was granted a scholarship to study in the

Pan-american school of agriculture (Zamorano), which is one of the most prestigious

agricultural schools in the area. At Zamorano, he was trained in areas related to food

technology with specialization in processing of dairy and meat products. After his graduation

from Zamorano he moved to Laurinburg, NC, where he started a manager trainee program

with Murphy Brown. The two main reasons for leaving his country were to learn the English

language and to pursue higher education degree in a US university. After one year in the

training program he was promoted as night shift supervisor and was the responsible to

oversee the production of approximately 10,000 tons of pelleted feed per week. In 2009, he

was granted a research assistantship in the Department of Poultry Science at North Carolina

State University (NCSU). At NCSU, Wilmer has focused on the interrelationships between

feed milling, nutrition, and physiology in poultry and swine. He is also a member of a team

that investigates a wide range of husbandry, nutrition, and feed milling issues.

iv

ACKNOWLEDGMENTS

I would like to thank my advisory committee Dr. John Brake, Dr. Peter Ferket, Dr. Charles

Stark, Dr. Mark Knauer, and Dr. Vernon Felts as well as Dr. Adam Fahrenholz for their

support and advice. A special appreciation is expressed to Dr. Charles Stark for giving me

the opportunity to come to the U.S. initially to work with Murphy Brown and then for

accepting me as his graduate student. I would like to express my sincere gratitude to Dr. John

Brake and Dr. Peter Ferket for being excellent mentors, friends, and advisors. I would like to

express my most sincere gratitude to Dr. Diego Bohorquez and Dr. Leonel Mejia for having

encouraged me to continue with my studies and for their continual support through my years

as graduate student. Thanks to my beloved girlfriend Indira Medina for her unconditional

love and support. Thanks to the graduate students in the Poultry and Animal Science

Departments Manuel Costa, Marcelo Dalmagro, Basheer, Satid, Amy, Marissa, Coltin,

Ayuub, Ilana, Rasha, Frank, David Rosero, Michael Shields, Santa Maria Mendoza, Oswaldo

Medina, Tiago Pasquetti and others for their friendship and for making my time at NC State

an unforgettable experience. Thanks to the feed mill manager Shawn Bradshaw, the farm

crew Terry, Lory, and Scott as well as all the undergraduates students that assisted me during

my research trials.

v

TABLE OF CONTENTS

LIST OF TABLES ................................................................................................................. x

LIST OF FIGURES.............................................................................................................. xii

CHAPTER I. LITERATURE REVIEW.............................................................................. 1

1.1. INTRODUCTION................................................................................................. 2

1.2. CORN STRUCTURE AND COMPOSITION...................................................... 4

1.3. ETHANOL PRODUCTION.................................................................................. 6

1.3.1. Grain receiving........................................................................................ 8

1.3.2. Grinding.................................................................................................. 8

1.3.3. Cooking and liquefaction........................................................................ 9

1.3.4. Saccharification and fermentation........................................................ 10

1.3.5. Distillation and further co-product processing..................................... 11

1.4. DDGS IN ANIMAL NUTRITION...................................................................... 12

1.4.1. Nutrient variability of DDGS................................................................ 13

1.4.2. Amino acid content and digestibility of DDGS.................................... 17

1.4.3. Metabolizable energy level of DDGS................................................... 19

1.4.4. Flow and storage of DDGS................................................................... 20

1.5. PELLETING........................................................................................................ 22

1.5.1. Measuring pellet quality....................................................................... 24

1.5.2. Pellet quality and feed mill efficiency.................................................. 25

1.6. PARTICLE SIZE REDUCTION......................................................................... 26

1.7. HYPOTHESES AND RESEARCH OBJECTIVES............................................ 28

vi

1.8. REFERENCES.................................................................................................... 32

CHAPTER II. EFFECT OF FURTHER GRINDING DDGS AND SBM ON PELLET

QUALITY IN SWINE DIETS............................................................................................. 47

2.1. ABSTRACT......................................................................................................... 48

2.2. INTRODUCTION............................................................................................... 49

2.3. MATERIAL AND METHODS........................................................................... 51

2.3.1. Diets...................................................................................................... 51

2.3.2. Data collection and laboratory analyses............................................... 52

2.3.2. Statistical analyses................................................................................ 53

2.4. RESULTS AND DISCUSSION.......................................................................... 54

2.5. TABLES AND FIGURES................................................................................... 58

2.6. REFERENCES.................................................................................................... 64

CHAPTER III. EFFECT OF PARTICLE SIZE, DDGS INCLUSION, AND PELLET

QUALITY ON BROILER LIVE PERFORMANCE AND GASTROINTESTINAL

DEVELOPMENT................................................................................................................. 68

3.1. ABSTRACT......................................................................................................... 69

3.2. INTRODUCTION............................................................................................... 70


3.3.1. DDGS analyses..................................................................................... 72

3.3.2. Diets...................................................................................................... 72

3.3.3. Bird husbandry...................................................................................... 73

3.3.4. Data collection and laboratory analyses............................................... 74

3.3.5. Ileal analyses......................................................................................... 76

vii

3.3.6. Statistical analyses................................................................................ 76

3.4. RESULTS AND DISCUSSION.......................................................................... 76

3.4.1. Feed manufacturing.............................................................................. 76

3.4.2. Broiler live performance....................................................................... 77

3.4.3. Organ development............................................................................... 79

3.4.4. Nitrogen and energy digestibility.......................................................... 80

3.5. TABLES AND FIGURES................................................................................... 82

3.6. REFERENCES.................................................................................................... 89

CHAPTER IV. EFFECT OF INCLUSION LEVEL AND METHOD OF ANALYSIS

FOR CRUDE FAT OF DDGS ON NUTRIENT DIGESTIBILITY, FOOTPAD

LESIONS, AND BROILER LIVE PERFORMANCE DEVELOPMENT..................... 95

4.1. ABSTRACT......................................................................................................... 96

4.2. INTRODUCTION............................................................................................... 97


4.3.1. DDGS analyses..................................................................................... 99

4.3.2. Diets...................................................................................................... 99

4.3.3. Bird husbandry.................................................................................... 100

4.3.4. Data collection and laboratory analyses............................................. 101

4.3.5. Ileal analyses....................................................................................... 103

4.3.6. Statistical analyses.............................................................................. 103

4.4. RESULTS AND DISCUSSION........................................................................ 104

4.4.1. Feed manufacturing............................................................................ 104

4.4.2. Broiler live performance..................................................................... 106

viii

4.4.3. Nutrient digestibility and footpad lesions........................................... 108

4.5. TABLES AND FIGURES................................................................................. 110

4.6. REFERENCES.................................................................................................. 117

CHAPTER V. EFFECT OF DDGS PARTICLE SIZE AND PELLET QUALITY ON

GROWER-FINISHER PIG PERFORMANCE.............................................................. 121

5.1. ABSTRACT....................................................................................................... 122

5.2. INTRODUCTION............................................................................................. 123

5.3. MATERIAL AND METHODS......................................................................... 124

5.3.1. Diets.................................................................................................... 124

5.3.2. Animal husbandry............................................................................... 125

5.3.3. Data collection and laboratory analyses............................................. 127

5.3.4. Statistical analyses.............................................................................. 128

5.4. RESULTS AND DISCUSSION........................................................................ 128

5.4.1. Feed manufacturing............................................................................ 128

5.4.2. Swine performance............................................................................. 130

5.5. TABLES AND FIGURES................................................................................. 133

5.6. REFERENCES.................................................................................................. 141

CHAPTER VI. INTEGRATION OF CONCEPTS AND FINDINGS FROM

RESEARCH STUDIES...................................................................................................... 145

6.1. INTRODUCTION............................................................................................. 146

6.2. EFFECTS OF DDGS INCLUSION ON PELLET QUALITY ........................ 147

6.3. EFFECTS OF FURTHER GRINDING DDGS ON PELLET QUALITY AND

BROILER AND SWINE PERFORMANCE........................................................... 148

ix

6.4. EFFECT OF PERCENTAGE PELLET FINES ON BROILER AND SWINE

LIVE PERFORMANCE........................................................................................... 150

6.5. MAXIMUM INCLUSION OF DDGS BASED UPON FORMULATION

STRATEGIES........................................................................................................... 151

6.6. REFERENCES.................................................................................................. 153

x

LIST OF TABLES

CHAPTER I

Table 1. Average proximate composition of corn (% dry matter)............................... 3

Table 2. Average nutrient composition of DDGS from ethanol plants...................... 15

Table 3. Comparison of gross energy (GE), DE, and ME estimates among DDGS

sources in pig diets ..................................................................................................... 17

Table 4. The stepwise regression equation to predict amino acid levels based on the

proximate values of moisture, crude protein (CP), fat, and fiber .............................. 18

CHAPTER II

Table 1. Composition and calculated contents of the experimental diets (% as fed

basis)........................................................................................................................... 58

Table 2. Descriptive statistics of the experimental diet............................................. 59

Table 3. Particle size distribution of corn, soybean meal, and DDGS ...................... 60

Table 4. Effect of particle size and inclusion of DDGS on pellet durability index

(PDI) and feed production rate .................................................................................. 61

CHAPTER III

Table 1. Determined and calculated chemical composition of the distillers dried grain

with solubles (DDGS) (% as-fed basis, unless stated otherwise) as received from the

supplier........................................................................................................................ 82


basis)........................................................................................................................... 83

Table 3. Effect of particle size and DDGS inclusion on pellet durability index (PDI)

and feed pellet production rate.................................................................................... 84

Table 4. Effect of particle size, DDGS inclusion, and percentage feed fines on BW,

feed intake, and feed conversion ratio (FCR) of broilers from 1 to 42 d of

age…………………………………………………………………………………... 85

Table 5. Effect of particle size, DDGS inclusion, and percentage feed fines on

relative gizzard and proventriculus weight at 42 d of age ........................................ 86

xi

Table 6. Effect of particle size, DDGS inclusion, and percentage feed fines on

nitrogen (N), crude protein (CP), and energy utilization (AME, AMEn, and GE) of

male broilers from 1 to 42 d of age ............................................................................ 87

CHAPTER IV


basis)......................................................................................................................... 110

Table 2. Effect of inclusion level and metabolizable energy value of DDGS on pellet

durability index (PDI) and pellet production rate..................................................... 111

Table 3. Effect of inclusion level and metabolizable energy value of DDGS on BW,

feed intake, and feed conversion ratio (FCR) of broilers from 1 to 49 d of age....... 112

Table 4. Effect of inclusion level and metabolizable energy value of DDGS on

protein, fat digestibility, and footpad lesion score at 49 d of age............................. 113

CHAPTER V

Table 1. Determined and calculated chemical composition of the distillers dried grain

with solubles (DDGS) (% as-fed basis, unless stated otherwise) as received from the

supplier...................................................................................................................... 133

Table 2. Composition and calculated contents of the grower, developer, and finisher

diets (% as fed basis)................................................................................................. 134

Table 3. Particle size distribution of the distillers dried grains with solubles (DDGS)

used during the experiment....................................................................................... 135

Table 4. Descriptive statistics for pellet quality....................................................... 136

Table 5. Effect of the particle size of distillers dried grain with solubles (DDGS) on

percentage fines and standard and modified pellet durability index (PDI).............. 137

Table 6. Descriptive statistics for pig live performance........................................... 138

Table 7. Effect of the particle size of distillers dried grains with solubles (DDGS) and

percentage pellet fines on body weight of grower-finisher pigs............................... 139


percentage pellet fines on average daily gain, average daily feed intake, and feed:gain

of grower-finisher pigs.............................................................................................. 140

xii

LIST OF FIGURES

CHAPTER I

Figure 1. Corn production by county and location of ethanol plants in USA ............. 4

Figure 2. Components of the corn kernel .................................................................... 6

Figure 3. Overview of dry grind process of ethanol production ............................... 12

CHAPTER II

Figure 1. Average particle size and particle size distribution of soybean meal used in

swine finishing diets as received (coarse-1070 µm) and after grinding (fine-467 µm)

in a hammermill equipped with a 1.6 mm screen ...................................................... 62

Figure 2. Average particle size and particle size distribution of DDGS used in swine

finishing diets as received (coarse-677 µm) and after grinding (fine-483 µm) in a

hammermill equipped with a 1.6 mm screen ............................................................. 63

CHAPTER III

Figure 1. Average particle size and particle size distribution of DDGS used in broiler

diets during the grower period as received (coarse-745 µm) and after grinding (fine-

482 µm) in a hammermill equipped with a 1.6 mm screen........................................ 88

CHAPTER IV

Figure 1. Relationship between pellet durability index (PDI) and amount of fat added

in the mixer in grower diets containing 0, 15, and 30% DDGS analyzed by two

methods of crude fat analysis (Acid hydrolysis (AH)-method 154.02 and ether extract

(EE)-method 990.03; AOAC, 2006))........................................................................ 114

Figure 2. Relationship between pellet durability index (PDI) and amount of fat added

in the mixer in finisher diets containing 0, 15, and 30% DDGS analyzed by two

methods of crude fat analysis (Acid hydrolysis (AH)-method 154.02 and ether extract

(EE)-method 990.03; AOAC, 2006))........................................................................ 115

Figure 3. Relationship between nitrogen digestibility and incidence of footpad

lesions (FPL) as measured by the footpad lesion score in diets containing 0, 15, and

30% DDGS analyzed by two methods of crude fat analysis (Acid hydrolysis (AH)-

method 154.02 and ether extract (EE)-method 990.03; AOAC, 2006))................... 116

1

CHAPTER I

LITERATURE REVIEW

2

1.1. INTRODUCTION

The increased usage of animal feed ingredients as raw materials for the production of

ethanol has increased U.S. production of biofuels by 82% from 2000 to 2008 (Schmidt et al.,

2012). Increased ethanol production has resulted into increased production of distillers dried

grains with solubles (DDGS) (Shurson, 2003). Distillers dried grains have been produced

after fermenting the starch fraction of grains to produce ethanol and have become the main

co-product of the ethanol and beverage industries. The residues that have remained after

fermentation have been termed “distillers wet grains or whole stillage” and have been

blended with the “condensed distillers solubles” (CDS, also know as syrup) to produce the

final DDGS. If the whole stillage was dried without adding the solubles, the product was

called distillers dried grains (DDG) (Pahm et al., 2008a).

Condensed distillers solubles has been reported to contain high levels of vitamins, fat,

and protein with low levels of fiber, and have yielded around 91% of the digestible energy

value of corn (Cruz et al., 2005). The DDGS have contained mainly the non-fermentable

components of the grains used to produce ethanol, but since the fermentation has not been

100% efficient, DDGS has also contained some residual sugars (Spiehs et al., 2002; Belyea

et al., 2004; Singh et al., 2005). Therefore, DDGS has become a valuable source of energy,

protein, water-soluble vitamins, and minerals (Batal and Dale, 2006; Ganesan et al., 2009;

Shalash et al., 2009) in poultry and swine diets.

Corn has been the major feed ingredient used for ethanol production and has

accounted for approximately 97% of the total grains used, followed by sorghum, which has

accounted for 2%, with the remaining 1% produced from other crops or by-products of

3

beverage production (Nichols and Bothast, 2008). The choice to use a particular ingredient

has depended upon the geographical location, costs, and availability among other factors.

Most ethanol plants have been concentrated in the Midwest and north-central portions of the

United States, where most of the corn has been produced (Figure 1). However, in recent

years ethanol facilities have been built in other states closer to the ethanol markets.

On a dry matter basis the corn kernel has been reported to contain approximately 75%

starch, 8.9% protein, 4.0% oil, 1.5% ash, 1.7% simple sugars, and 8.9% fiber (Watson,

2003), but since most of the starch has been fermented to produce ethanol the remaining non-

fermentable nutrients became concentrated about three-fold in the DDGS.

Table 1. Average proximate composition of corn (% dry matter)

Component Starch Fat Protein Ash Sugar Fiber

Whole Kernel 73.4 4.4 9.1 1.4 1.9 9.5

Kernel Fractions ———————————— (%) ————————————

Endosperm 98.1 15.4 73.3 17.9 28.6 27.00

Germ 1.5 82.6 26.2 78.4 69.3 16.00

Pericarp 0.6 1.3 2.6 2.9 1.2 51.00

Tip Cap 0.1 0.8 0.9 1.0 0.8 0.01

Source: Watson (2003)

4

Source: USDA, 2012.

Figure 1. Corn production by county and location of ethanol plants in USA.

1.2. CORN STRUCTURE AND COMPOSITION

The kernel has been described as being comprised of pericarp, endosperm, germ, and

tip cap (Singh et al., 2007) (Figure 2). The pericarp was the seed coat that covered the corn

kernel and served to protect and support the growing endosperm and embryo during seed

development. The part of the hull overlying the embryo was known as the tip cap, which was

the attachment point to the cob (Kent and Evers, 1994). The endosperm was the largest

structural part of the grain, which has accounted for 80 to 85% of the grain weight, and

5

contained large amounts of starch and storage proteins (Watson, 1994; Reyes et al., 2011).

The nutrients in the endosperm were mobilized to support growth of the embryonic axis at

the onset of germination (Fincher, 1989). Starch has been found to be the most abundant

carbohydrate in corn and the main form of stored energy (Liu, 2012). In the production of

ethanol, starch has been the key component as it has been converted into glucose molecules,

which could be fermented to produce ethanol and CO2 (Bothast and Schlicher, 2005). In

addition, the endosperm contained around 6.9-10.4% protein stored in the endoplasmic

reticulum (Earle et al., 1946).

The aleurone tissue was reported to be a layer of single cells found just below the

pericarp and surrounding the starchy endosperm (Kent and Evers, 1994). Aleurone cells

exhibited high concentrations of proteins, lipids, vitamins, and minerals and provided sites

for synthesis and secretion of alpha amylase and a range of hydrolytic enzymes responsible

for solubilizing of the energy reserves of the grain at the onset of germination (Baulcombe et

al., 1984; Liu, 2012). Contrasted to the starchy endosperm, aleurone cells accumulated their

proteins inside vacuoles instead of the endoplasmic reticulum (Reyes et al., 2011).

The germ or embryo has been described as comprising between 8 – 10% of the dry

weight of the kernel and contained protein, oil, as well as starch (Watson, 1994).

Approximately 83% of the fat and 26% of the protein of the corn kernel were contained in

the germ (Earle et al., 1946). Indeed, there has been a positive correlation between the

percentage embryo and the lipid content of the corn kernel (Hopkins et al., 1974).

Proteins in corn have been classified based on their solubility with albumins soluble

in water, globulins soluble in salt solutions, prolamins soluble in alcohol/water solutions, and

6

glutelins soluble in acids (Shewry and Thatam, 1990). Albumins and globulins were

concentrated in germ, aleurone, and pericarp with small amounts found in the endosperm

(Hoseney, 1994). During the fermentation process to produce ethanol the proteins in the corn

have typically remained unchanged and have become concentrated around three-fold in the

DDGS. Therefore, if the initial protein content in the corn was 9%, the final DDGS contained

approximately 27% protein. In addition, lipids exhibited minimal change during the

fermentation process and have ended up mostly in the DDGS.

Figure 2. Components of the corn kernel (U.S. Grains Council, 2011).

1.3. ETHANOL PRODUCTION

At the time of this writing the USA had 211 ethanol facilities and more than 90% of

them used corn as their ingredient (RFA, 2014). Indeed, approximately 27.3% of corn

produced in the U.S. was diverted to ethanol production (National Corn Growers

Association, 2012). Corn was converted into ethanol primarily by two processes: wet milling

7

and dry grinding (Rausch and Belyea, 2006). The wet milling process required high capital

investment, was required to process large quantities of corn, and produced large volumes of

ethanol and co-products to justify production costs (Belyea et al., 2004). In wet milling, corn

was fractionated into its components, which included starch, fiber, gluten, and germ (Bothast

and Schlicher, 2005). The starch was then converted into simple sugars and used to produce

glucose, dextrose, high fructose corn or ethanol by yeast fermentation. The germ was de-

oiled to produce corn oil or dehydrated to produce germ meal. Proteins were also

concentrated and used mainly in feeds for non-ruminants and companion animals (Raush and

Belyea, 2006). The wet milling industry had greater flexibility due to the amount of co-

products produced (Bothast and Schlicher, 2005).

The most popular process recently used to produce ethanol in the USA has been

recently the dry grind process (Figure 3), which has accounted for over 80% of the total

ethanol production (RFA, 2009). In dry grind processing, the corn kernel was ground into a

coarse flour of around 600 µm in particle size without fractionating. Dry-grind facilities

required less equipment and were less capital intensive, but fewer co-products were produced

than the wet milling process (Raush and Belyea, 2006). In both processes, unfermented

nutrients (protein, fiber, and minerals) were converted into DDGS. Dry grind ethanol

manufacturing has typically resulted in three main products that included ethanol, DDGS,

and carbon dioxide (CO2). As a rule of thumb, for every bushel of corn (~56 lbs; 25.4 kg)

approximately 2.8 gallons of ethanol (8.2 kg), 18 lbs (8.2 kg) of DDGS, and roughly 18 lbs

(8.2 kg) of CO2 were produced. Dry grinding consisted of several key steps including grain

receiving, distribution, grinding, cooking, liquefaction, saccharification, fermentation (mostly

8

simultaneous saccharification and fermentation), distillation, and co-product recovery (Naidu

et al., 2007; Liu, 2009).

1.3.1. Grain Receiving

Corn was typically delivered into the ethanol plant by truck or by rail. Before

unloading, the grain was sampled and tested for mycotoxins, moisture, foreign material, and

mold damage. Mycotoxin levels were monitored carefully as these typically became

concentrated by approximately three fold in DDGS (Bothast et al., 1992; Bennett and

Richard, 1996; Zhang et al., 2009). This has been a major concern because mycotoxins have

been reported to significantly decrease the performance of poultry and swine species (Doerr

et al., 1983; Verma et al., 2004; Verma et al., 2007). After testing, the grain was dumped into

an underground receiving pit and sent to the grain storage area.

1.3.2. Grinding

The purpose of grinding was to reduce particle size and facilitate water penetration

during the cooking process. The whole kernel was ground by passing it through hammermills

equipped with screens with relatively small openings of approximately 3.2–4.8 mm diameter

(Bothast and Schlicher, 2005) or through roller mills with one or two sets of rolls. Grinding

also increased the surface area of the starch substrate particles available to enzymes and yeast

in the subsequent ethanol production steps. Although roller mills were more energy efficient

than hammermills and tended to produce more uniform particles with fewer fines, roller mills

were not often used in ethanol plants as they had higher initial costs of installation (Koch,

2002). Hammermills were the most common grinding equipment due to their higher

9

throughput capacity and efficiency. The particles produced with a hammermill were

generally spherical and their distribution varied widely with mostly small particles and some

large particles (Koch, 2002). The resulting average particle size and distribution was affected

by a number of factors such as screen size, hammer tip speed, number of hammers, air

assisted equipment, roll openings, moisture content, sharpness of the hammers, size and

integrity of the screens, presence of foreign material among others (Dupin et al., 1997).

Particle size and particle size distribution were reported to affect ethanol yield and the final

nutritional composition of the DDGS (Kelsall and Lyons, 2003; Naidu et al., 2007). In fact,

Kelsall and Lyons (1999) reported that by reducing the screen size of the hammermill from 8

mm to 5 mm, there was an increase in the ethanol yield from 2.45 to 2.65 gallons per bushel

(~ 56 lbs) of corn.

1.3.3. Cooking and Liquefaction

After grinding, corn flour was mixed with water and recycled stillage to form slurry

with approximately 30% solids (Rosentrater et al., 2012). This process initiated the

separation of soluble proteins from non-starch bound lipids and sugars. The slurry was

pumped into a cooking system (jet cooker) where it was heated to temperatures of 110-150ºC

using pressurized steam. Cooking sterilized the mash, broke down the crystalline structure of

the starch granules as well as the chemical bonds between proteins and sugars, initiated

starch gelatinization, and reduced the viscosity of the slurry (Kelsall and Lyons, 2003;

Rosentrater et al., 2012). During the cooking process, the pH was adjusted to between 5.5

and 6.0 through the addition of sulfuric acid (H2SO4) or ammonia. Cooking also killed lactic

10

acid producing bacteria in the grain, which have been reported to negatively affect ethanol

production by reducing the pH of the medium and creating an unfavorable environment for

yeast (Makanjuola et al., 1992; Huang et al., 1996; Franchi et al., 2003; Graves et al., 2006).

After cooking, the slurry was sent to a liquefaction tank where it was cooled to

around 60ºC. Gelatinization of the starch occurred at temperatures between 50 to 70ºC and

was controlled by the addition of amylolytic enzymes at a rate of between 0.04 and 0.08%.

The rate of starch gelatinization influenced the extent of conversion of starch into glucose

chains in the subsequent steps (Lin and Tanaka, 2006)

1.3.4. Saccharification and Fermentation

During the saccharification step α-amylase was added to degrade starch polymers into

short chain molecules and form a mash. The addition of amylolytic enzymes accounted for

around 10-20% of the total ethanol production costs (Gregg et al., 1998). Once the starch was

cleaved into small dextrins, the mixture was sent to a fermentation tank. Residence times in

the fermentation tank ranged from 40 to 72 h, depending upon the temperature and initial

particle size of the grains. Since particle size greatly influenced the fermentation efficiency,

ethanol facilities have reduced the particle size of the flour in order to increase the ethanol

yield. Glucoamylase and yeast (Saccharomyces cerevisiae) were added in the fermentation

tank where glucoamylase hydrolyzed the α-1,4 and α-1,6 bonds in dextrins into glucose and

maltose and the yeast converted these mono and disaccharides into ethanol and CO2.

11

1.3.5. Distillation and Further Co-products Processing

At the end of fermentation the product was termed “beer” and contained around 12%

ethanol. The beer was stored in a tank called a “beer well” until transferred to distillation

columns where the ethanol was separated from the whole stillage (non-fermented solids of

corn, yeast, and water). The separation of the water and ethanol was accomplished by the use

of a rectifier column that produced 190-proof ethanol (95%), which was then sent to a

molecular sieve column and converted to 200-proof ethanol (100%).

The whole stillage with 13 to 17% solids (protein, minerals, fiber, fat, etc.) was

withdrawn from the bottom of the distillation unit and centrifuged to produce wet cake and

thin stillage (Raush and Belyea, 2006). The wet cake, which was a more concentrated form

of whole stillage, contained between 35 to 50% solids. The thin stillage that contained

between 5 to 10% solids was sent through an evaporator where solids were concentrated into

syrup that contained 25 to 55% solids. The syrup was subsequently blended with the wet

cake before entering the drier. The mixture of wet cake and syrup was dried to generate the

DDGS, which typically contained 31.3% crude protein, 11.9% crude fat, 10.2% fiber, and

4.6% ash (Belyea et al., 2004). On a dry matter basis 100 kg corn has typically yielded 70 kg

starch, which produced 77.8 kg of glucose. The glucose was subsequently fermented to

produce 39.8 kg of ethanol and 38.0 kg of carbon dioxide (Maisch, 2003). Quality control

procedures have assured consistency in the amount of protein, fat, fiber, and moisture as well

as to control mycotoxin levels.

12

Figure 3. Overview of dry grind process of ethanol production. Reproduced from Nichols et

al. (2006).

1.4. DDGS IN ANIMAL NUTRITION

Distillers dried grains with solubles was not typically included in poultry and swine

diets, but increased production of ethanol increased the supply of DDGS while decreasing the

supply of corn and encouraged the use of higher percentages of DDGS in livestock diets

(Waldroup, 2007). As the usage of DDGS increased, there was the necessity to study the

maximum inclusion of DDGS that could be fed without affecting animal performance,

animal welfare, and feed efficiency. Recently, there has been an abundance of research to

precisely determine the nutrient content of DDGS in order to take full advantage of its value

in poultry and swine diets (Fiene et al., 2006). According to Lumpkins et al. (2004), up to 6%

13

DDGS could be included in broiler starter diets and 12 to 15% in grower and finisher diets.

In another study, Loar et al. (2010) reported that 8% DDGS could be included from 0 to 14 d

of age and 15% from 14 to 42 d of age without adverse effects on broiler live performance

and feed efficiency. In diets for commercial layers approximately 10-12% could be fed

without affecting egg production (Lumpkins et al., 2005). The maximum inclusion of DDGS

has been influenced by the methodology used during feed formulation. If the metabolizable

energy (ME) content of diets was maintained constant by the addition of supplemental fat, up

to 25% DDGS could be used without adverse effects on live performance and feed efficiency

(Waldroup et al., 1981), but if the ME was allowed to decline as the inclusion of DDGS

increased, only 15% could be fed. Some concerns regarding DDGS usage were related to

nutrient variability, particularly when high levels were used (Noll et al., 2007b). The major

concerns were variation in ME content, bioavailability of amino acids such as lysine,

bioavailability of phosphorus, and variation in sodium content (Waldroup et al., 2007). From

the feed milling perspective, the major concerns were related to poor ingredient flow

characteristics and decreased pellet quality. Therefore, it has become essential to precisely

know the nutritional value and pelleting characteristics of DDGS in order to utilize this

ingredient effectively in poultry and swine diets.

1.4.1. Nutrient Variability of DDGS

The nutrient content of DDGS has varied considerably from different sources (Spiehs

et al., 2002; Belyea et al., 2010; Liu, 2008). Many factors have been found to influence

nutrient variability of DDGS including cereal type and variety, amylose and amylopectin

14

content (Singh and Graeber, 2005; Sharma et al., 2007), location of the ethanol plant

(Whitney et al., 2000; Fastinger and Mahan, 2006), type and amount of additives used during

fermentation, water quality, and concentration of solids (Rausch and Belyea, 2006) among

others. However, the main factor that influenced the nutrient content of DDGS was the

amount of distillers solubles (thin stillage) added to the whole stillage (Goodson and

Fontaine, 2004; Waldroup et al., 2007). Noll et al. (2007a) observed that as the amount of

thin stillage added to the whole stillage was increased, there was an increase in fat and ash

content in the final DDGS. In the same study, protein and amino acid content did not change

appreciably, but true amino acid digestibility coefficients were negatively correlated with

solubles addition, likely because a more severe heat treatment was required to decrease the

moisture level in the final DDGS. Heat treatment has been reported to deteriorate protein

quality by destroying heat-sensitive amino acids, particularly lysine. The Maillard reaction,

which is the most common type of heat damage, involves the reduction of the ε-NH2 group

of lysine with a carbonyl group of a reducing sugar (Pahm et al., 2008a). Previous research

demonstrated that the components of DDGS with the highest nutritional variation were crude

fiber, ADF, NDF, ash, phosphorus, and lysine (Table 2).

There has been a considerable variability in many of the essential nutrients in DDGS,

particularly with regards to certain amino acids such as arginine, leucine, and lysine.

According to Waldroup el at. (2007), corn itself has varied in nutrient content and since the

nutrients in corn other than starch became concentrated in DDGS about three fold, any

variation in corn would exacerbate the nutrient variability in the DDGS. The swine industry

has conducted several research trials to establish the digestible energy (DE) and ME values

15

of various DDGS sources (Stein et al., 2006; Pedersen et al. 2007; Stein et al., 2009;

Mendoza et al., 2010; Anderson et al. 2011) (Table 3). The average ME value of DDGS has

been approximately 96% of the value of corn, but has ranged from 88.9 to 105.7% (Shurson,

2007), depending particularly upon the level of crude fat.

Table 2. Average nutrient composition of DDGS from ethanol plants.

Component

Reference1

Average 1 2 3 4 5

n = 118 n = 150 n = 20 n = 5 n = 8

Mean CV2 Mean SD Mean CV Mean Mean SD

DM basis 88.9 1.7 89.9 1.71 88.0 0.9 - - - 89.4

Crude protein 30.2 6.4 26.1 2.32 - - - 28.12 - 26.4

Fat 10.9 7.8 9.9 2.80 14.0 4.8 - - - 10.1

Fiber 8.8 8.7 6.3 1.55 - - - - - 7.0

Ash 5.8 14.7 4.4 0.87 4.0 5.0 - - - 4.7

Arg 1.2 9.1 1.1 0.13 - - 1.0 1.09 0.16 1.1

His 0.7 7.8 - - - - 0.65 0.69 0.06 0.7

Ile 1.1 8.7 0.9 0.18 - - 1.0 0.97 0.06 1.0

Leu 3.5 6.4 2.9 0.63 - - 3.1 3.05 0.14 3.0

Lys 0.8 17.3 0.7 0.17 0.7 11.6 0.6 0.71 0.16 0.7

Met 0.5 13.6 0.5 0.12 0.5 9.7 0.5 0.54 0.06 0.5

Cys - - 0.5 0.10 0.5 11.3 ND 0.56 0.04 0.5

Phe 1.3 6.6 - - - - 1.3 1.31 0.04 1.3

Thr 1.1 6.4 0.9 0.17 0.9 6.0 0.9 0.96 0.06 1.0

Trp 0.2 6.7 0.2 0.03 - - 0.3 0.20 0.05 0.2

Val 1.3 7.2 1.3 0.22 - - 1.3 1.33 0.07 1.3

Ser - - - - - - 1.0 1.09 0.07 1.1 1 1 = Spiehs et al. (2002); 2 = Fiene et al. (2006); 3 = Parsons et al. (2006); 4 = Fastinger et al. (2006); Batal and

Dale (2006).

In the USA more than 50% of the ethanol facilities have extracted the oil principally

from corn before producing the DDGS, which increased the variability of the crude fat

content and ME values in the final DDGS (U.S. Grains Council, 2011) and produced DDGS

that were less desirable to be used in poultry and swine diets. Perryman et al. (2013) reported

16

a MEn of 1,975, 2,644, and 3,137 kcal/kg for low (6.06% ether extract (EE)), medium

(8.80% EE), and high (11.59% EE) DDGS when fed to broilers from 21 to 30 d of age.

Prediction equations have been developed to estimate ME based on the chemical composition

(Batal and Dale, 2006; Cozannet et al., 2010). Although the use of prediction equations have

ameliorated the adverse consequences of nutrient variability between DDGS sources, the

ethanol industry did not have guidelines or recommendations regarding the most appropriate

analytical methods to measure the chemical composition of DDGS. This has led to confusion

and misinterpretation of data for proximate analysis and formulation issues regarding to the

ME values assigned to the nutrient matrix of DDGS. The American Feed Industry

Association (AFIA, 2007) conducted a study to evaluate the efficacy, applicability, and

variability (both intra and inter laboratory variation) of the most common methods used for

analysis of moisture/loss on drying, crude protein, crude fat, and crude fiber. The final

recommendations were based upon the coefficient of variation for both the intra and inter

laboratory variations. The recommended methods were NFTA 2.2.2.5 Lab Dry Matter (105

ºC/3 hr) for moisture analyses, AOAC 990.03 and AOAC 2001.11 for crude protein, AOAC

945.16 for ether extract, and AOAC 978.10 for crude fiber (AOAC, 2005). Nevertheless, the

influence of the variation in these methods has not been tested to determine their effect on the

performance of poultry.

17

Table 3. Comparison of gross energy (GE), DE, and ME estimates among DDGS sources in

pig diets.

Component

Reference1

1 2 3 4 5

n = 10 n = 10 n = 4 n = 17 n = 6

Mean Range Mean Range Mean Range Mean Range Mean Range

GE

(kcal/kg)

5,426 5,372-

5,500

5,434 5,272-

5,592

5,593 5,483-

5,691

5,311 5,177-

5,421

5,420 5,314-

5,550

DE (Kcal/kg) 3,556 3,382-

3,811

4140 3,947-

4,593

4,029 3,920-

4,252

3,954 3,663-

4,107

4072 3,705-

4,332

ME (Kcal/kg) -

-

3,897 3,674-

4,336

3,790 3,575-

3,976

3,700 3,381-

3,876

3,750 3,414-

4,141

CP (%) 30.9 28.2-

32.7

32.2 29.8-

36.1

31.8 30.5-

33.1

30.3 27.3-

33.3

31.3 29.5-

34.1

NDF (%) 45.2 41.8-

49.1

27.6 23.1-

29.7

40.1 35.1-

45.2

34.6 25.3-

43.1

40.4 33.4-

49.1

Crude Fat

(%)

-

-

11.7 10.2-

12.1

13.2 10.9-

14.1

11.7 8.7-

14.6

11.4 10.2-

12.1 11 = Stein et al. (2006); 2 = Pedersen et al. (2007); 3 = Stein et al. (2009); 4 = Mendoza et al. (2010); Anderson

et al. (2011).

1.4.2. Amino Acid Content and Digestibility of DDGS

Poultry and swine nutritionists have been concerned not only with the variation in the

total amount of amino acids but also with variation in their digestibility, which has varied

depending upon the type and source of grain that has been used to produce the ethanol.

Nevertheless, studies have shown that variation has existed even in DDGS produced from the

same type of grain (Fastinger and Mahan, 2006; Pahm et al., 2008b). Lysine has been defined

as the first or second limiting amino acid in swine and poultry diets. Hence, its digestibility

has been a major concern when a high level of DDGS has been used (Noll et al., 2007b). The

digestibility of lysine in DDGS has usually been lower as compared to that in corn and SBM

(Batal and Dale, 2006).

18

During the drying process of DDGS, the material was exposed to high temperatures

increasing the Maillard reaction between lysine and reducing sugars (McGinnis and Evans,

1947; Warnick and Anderson, 1968; Cromwell et al., 1993). In one study, Fastinger and

Mahan (2005) reported DDGS to have an apparent ileal digestibility of lysine of only 27%,

which suggested that some sources of DDGS might be severely overheated. In a previous

study, Spiehs et al. (2002) measured the amino acids variability in DDGS and reported that

lysine exhibited the highest variability (CV = 17.3%) followed by methionine (CV = 13.6%).

Table 4 shows regression equations used to predict total amino acid content of DDGS from

proximate analyses values that included moisture, crude protein, fat, and fiber.

Table 4. The stepwise regression equation to predict amino acid levels based on the

proximate values of moisture, crude protein (CP), fat, and fiber.

Amino Acid Equation R2

Arginine Y = 0.07926 + 0.0398*CP 0.48

Cystine Y = 0.11159 + 0.01610*CP + 9.00244*Fat 0.52

Isoleucine Y= -0.23961 + 0.04084*CP + 0.01227*Fat 0.86

Leucine Y= -1.15573 + 0.13082*CP + 0.06983*Fat 0.86

Lysine Y= -0.41534 + 0.04177*CP + 0.00913*Fiber 0.45

Methionine Y= -0.17997 + 0.02167*CP + 0.01299*Fat 0.78

TSAA Y= -0.12987 + 0.03499*CP + 0.05344*Fat – 0.00229*Fat2

0.73

Threonine Y= -0.05630 + 0.03343*CP + 0.02989*Fat – 0.00141*Fat2

0.87

Tryptophan Y= 0.01676 + 0.0073*CP 0.31

Valine Y= 0.01237 + 0.04731*CP + 0.00054185*Fat2

0.81

Source = Fiene et al. (2006)

The amino acids above with high R2

values (Ile, Leu, Met, TSAA, and Val) were

predicted with most accuracy using the proximate analyses data. The use of color

measurements has been used as a tool to predict lysine digestibility: dark-colored DDGS has

19

been reported to have lower amino acid digestibility when compared with light colored

DDGS (Cromwell et al., 1993; Fastinger and Mahan, 2006).

Formulation decisions could also influence performance, especially if diets were

formulated on a crude protein basis rather than digestible amino acid basis. Shim et al. (2011)

conducted an experiment in which the diets were formulated on a digestible amino acid basis

and did not find statistical differences for BW gain, FCR, and mortality at 42 d of age in diets

containing 0, 8, 16, or 24% DDGS. In the study the authors utilized fixed formulation

minimums for Met, TSAA, Thr, Trp, Val, Ile, and Arg in order to maintain ideal digestible

amino acid ratios relative to Lys, hence protein level increased as the DDGS inclusion

increased in order to compensate the for the lower amino acid digestibility of DDGS as

compared to corn or SBM. In contrast, Lumpkins et al. (2004) formulated diets to a minimum

crude protein level and on a total amino acid basis and concluded that only 6% DDGS could

be safely used in starter diets followed by 12 to 15% in grower and finisher diets. According

to Shim et al. (2011), diets in earlier trials using DDGS were formulated using total amino

acids rather that digestible amino acids and minimum amino acids constraints were only set

for lysine, methionine, and TSAA.

1.4.3. Metabolizable Energy Levels of DDGS

Use of the correct ME level for DDGS during feed formulation has had a

considerable impact on the performance of poultry and swine (Fiene et al., 2006). Fastinger

et al. (2006) reported an average of 2,871 kcal/kg for five samples, which ranged from 2,484

to 3,014 kcal/kg. Using a larger sample size, Batal and Dale (2006) reported an average true

20

metabolizable energy (TME) value of 2,820 ± 82 kcal/kg, with a range of 2,490 to 3,190

kcal/kg for 17 samples. The same authors applied regression analyses and developed

prediction equations to calculate the TMEn of DDGS based on its proximate composition

(fat, protein, fiber, and ash). The major differences between the samples were in crude fat

content with lower variability in fiber and ash content. The best single indicator for TMEn

was the fat content (R2

= 0.29) but the addition of second, third, and fourth variables (fiber,

protein, and ash) improved the accuracy of the prediction equation (R2 = 0.43, 0.44, and 0.45,

respectively). For swine diets, Spiehs et al. (2002) calculated the DE and ME to be 3,990 and

3,749 kcal/kg, respectively, which were also higher than NRC values, likely due to higher

crude fat content (NRC, 1998). Stein et al. (2006) reported an average DE of 3,556 kcal/kg

with a range of 3,382 to 3,811 kcal/kg of DM (Table 3).

1.4.4. Flow and Storage of DDGS

Storage and handling of DDGS was initially very troublesome due to its poor

flowability during loading and unloading into storage bins (AURI and MCGA, 2005;

Rosentrater, 2006; Bhadra et al., 2009). During shipping, DDGS often caked and bridged,

which decreased its flow characteristics in the feed mill and resulted in additional shipping

costs (Schlicher, 2005; Bhadra et al., 2009) because of increased labor, machinery, and time

required to unload and handle the material (Rock and Schwedes, 2005). The use of anti-

caking agents such as calcium carbonate, which were previously used to enhance flow of

SBM have not been not approved to be used in DDGS because there were questions

regarding how they would perform in this application (Behnke, 2007). Poor flowability

21

characteristics also led to damage of the railcars during unloading as sledgehammers were

frequently used to hit the cars and induce flow (Ganesan et al., 2009).

Strategies such as controlling the amount of condensed distillers solubles added to the

wet cake and controlling the drying process were proposed to reduce flowability problems

(Kleinschmit et al., 2006). According to Behnke (2007) storing the DDGS at the ethanol

facility for five to seven days or until moisture equilibration was completed increased the

flowability of DDGS. Bhadra et al. (2009) reported that flowability decreased as moisture

content of DDGS increased. In a more recent study, Bhadra et al. (2013) concluded that the

flowability problems of DDGS were primarily due to variability of temperature during drying

and quantity of condensed distillers added to the wet cake, with a lesser effect of cooling

temperature. Another approach to improve flowability and decrease caking was to pellet the

DDGS at the ethanol facility, however this approach could increase grinding costs at the

receiving feed mill (Behnke, 2007). Rosentrater (2007) conducted a study in which 100% of

DDGS were pelleted using a commercial pellet mill and he reported that pelleting did not

affect its nutritional value. In addition, Tumuluru et al. (2010) reported the effects of process

variables on pellet quality of wheat DDGS and reported a higher pellet density, lower pellet

moisture, and higher pellet durability at low initial moisture content of the DDGS in the

presence of a high die temperature.

22

1.5. PELLETING

Pelleting was developed to force and shape bulk material through a die in order to

improve its physical characteristics and nutritional content (Kokić et al., 2013). As the

benefits of pelleting became more recognized in recent years, there has been an enormous

increase in the amount of feed that was pelleted by the swine and poultry industries (Zang et

al., 2009). Pelleting has been reported to be a combination of heat, friction, pressure, and

particle size reduction and has been shown to increase feed consumption (Abdollahi et al.,

2011), improve feed efficiency (Jensen, 2000), and increase BW (Frikha et al., 2009).

Pelleting has also been related to an improvement of dietary AME and apparent digestibility

of dry matter (Kilburn and Edwards, 2001; Svihus et al., 2004). The increased temperature

accomplished during pelleting has been shown to positively influence protein unfolding,

starch gelatinization, feed throughput, and pellet quality (Ravindran and Amerah, 2008).

Protein unfolding and partial denaturation of the native structure of protein has exposed

peptides linkages to enzymatic attack by endogenous proteases (Voragen et al., 1995;

Amerah et al., 2011). Heat treatment during pelleting has also increased starch gelatinization

to some extent. Gelatinization has been reported to increase the digestion and absorption of

the starch by enhancing its ability to absorb water and hence increased the speed at which the

amylolytic enzymes (endogenous and exogenous) disrupted the linkages of starch (alpha 1-4

and alpha 1-6) and converted it into simple sugars (Ravindran and Amerah, 2008).

In addition to increased starch gelatinization and protein denaturation, pelleting

improves performance and feed efficiency through decreased feed wastage and reduced

selective feeding. When giving an option to choose birds consumed coarse particles first

23

particularly as birds aged and became larger (Moran, 1982). Therefore, pelleting has

improved the likelihood of feeding a more uniform and balanced diet (Fahrenholz, 2012).

Pelleting has also improved performance by reducing the length of time and energy costs of

feeding periods. Poultry and swine have been reported to consume pelleted feed faster than

mash feed. In addition, Skoch et al. (1983) suggested that pelleting made the feed more

palatable by increasing its bulk density and by reducing dustiness, which increased feed

consumption and reduced time that the animals spent at the feeder. Indeed, Jensen et al.

(1962) reported that chicks fed mash diets spent 14.3% of their time at the feeder, while

chicks fed pelleted feed only spent 4.7%. Pelleting has improved performance efficiency

through decreased ingredient segregation, increased bulk density and reduced bridging

problems in bins. Agglomeration of the ingredients in the pellet enabled poultry and swine to

consume all ingredients and nutrients simultaneously and discouraged selective feeding.

Pelleting has also been reported to decrease nutrient segregation during transportation and

during storage in the bins (Behnke, 1994). Furthermore, pelleting has facilitated the inclusion

of ingredients with poor flowability characteristics (Stark, 2012).

Pelleted feed has allowed poultry and swine to consume their meals during their

limited time at the feeder. Behnke and Beyer (2002) reported that chicks fed pelleted diets

spend around 5% of their times eating at the feeder as compared to 15% for chicks fed mash

diets. Under conditions of ad libitum feeding, the total rate of growth was the major

determinant of feed efficiency as it resulted in a reduction in daily maintenance costs that use

feed and water without yielding product in terms of eggs, meat, etc. A chicken or pig

growing slowly would have similar daily maintenance costs as a chick or pig that was

24

growing more rapidly, but would produce less meat to counteract the fixed cost of

maintenance (Kleyn, 2013).

1.5.1. Measuring Pellet Quality

Pellet quality analyses have helped to assure that consistent quality feed was

produced at the feed mill. Pellet quality has been measured using various standard methods.

The two most popular methods used to measure pellet quality have been the Kansas State

University (KSU) method and the Holmen method. The KSU method or tumbling can test

was accepted as the standard method by the American Society of Engineers after it showed

an excellent correlation with the Stoke hardness test. This was a simple test in which the

pellets were tumbled in a specially designated box for 10 min in order to simulate the transfer

and handling of the feed (Fairfield, 1994). Pellet durability index (PDI) was calculated as the

ratio of fines after tumbling to the amount of whole pellets at the start of the test. Feed with a

higher PDI indicated that the manufactured pellets were more likely to remain intact before

feeding (Behnke and Beyer, 2002). The main purpose of the KSU tumble box method was to

predict the actual percentage of fines generated as the pelleted feed was subjected to abrasive

impact forces as it moved from the feed mill to the farm bin and then to the feeder in front of

the birds or pigs. However companies and nutritionists have modified the KSU method by

adding hex nuts or other modifiers in order to increase the impact forces inside the tester and

improve the ability to predict the true quality of the feed at the farm.

Holmen Pellet Tester was developed in England and therefore has been more

frequently used by the European feed industry. The Holmen method circulated pellets

25

through an air conveyance system for 30-120 second. Pellets were subjected to shear and

impact, which simulated the pneumatic transport used mainly in European countries rather

than the mechanical conveyance used in USA feed mills.

1.5.2. Pellet Quality and Feed Mill Efficiency

The addition of DDGS to poultry and swine diets has produced mixed results with

regards to pellet quality. According to Noll et al. (2007b), the addition of DDGS to pelleted

feed has had negative effects on feed mill performance. The main concerns during feed

manufacturing were the negative effect on pellet quality and pellet mill throughput (Behnke,

2007). Shim et al. (2011) reported a decrease in pellet quality from 81 to 61% in grower feed

and 74 to 50% in finisher feed when the inclusion of DDGS increased from 0 to 24%.

Fahrenholz et al. (2008) conducted two experiments varying the inclusion of DDGS from 0

to 40%. In the first experiment, the author reported no differences on pellet durability for

both standard and modified methods, however diets that contained 40% DDGS resulted in

10% lower production rate as compared to the control. In the second experiment the author

reported a decrease in pellet quality for the standard (90.3 to 86.6%) and modified (88.6 to

84.3%) PDI methods and decreased production rate (13%) as the inclusion of DDGS was

increased from 0 to 40%. Using similar levels, Stender and Honeyman (2008) reported a

decrease in pellet quality from 78.9 to 47.4% as the inclusion of DDGS was increased from 0

to 40%. The decrease in pellet quality of diets containing DDGS has been attributed to lower

starch content and consequently poorer binding properties (Behnke and Beyer, 2002). In

addition, DDGS possessed lower ME value than corn, therefore higher inclusions of DDGS

26

always required a higher amount of added fat in the mixer if caloric density had to be

maintained. Fat has been reported to work as a lubricant during the pelleting process to

reduce friction in the pellet die and impair pellet binding (Stark, 1994; Thomas et al., 1998).

Wang et al. (2007) reported an increase in the percentage of fines when more fat was added

to diets containing DDGS in order to retain isocaloric diets, but less variation in the

percentage fines when the level of fat was kept constant (Wang et al., 2008).

1.6. PARTICLE SIZE REDUCTION

Many feed ingredients such as cereal grains (corn, wheat, etc.) have been ground to

reduce particle size before their incorporation into poultry and swine diets (Zang et al.,

2009). The reduction in the particle size of grains during grinding has involved the disruption

of the outer seed coat and fracture of the endosperm (Amerah et al., 2007). The influence of

particle size on pellet quality and poultry and swine performance has been extensively

studied (Kilburn and Edwards, 2001; Peron et al., 2005; Parsons et al., 2006). Decreased

particle size increased the surface area of the digesta available for interaction with digestive

enzymes and was associated with improved digestibility (Goodband et al., 2002). Previously,

particle size was defined in general terms as fine, medium, and coarse (Goodband et al.,

2002). Currently there has been more interest in studying the effect of dietary particle size on

animal performance and a more accurate measurement of particle size has been developed

utilizing the geometric mean of the particles as well as size distribution (ASAE, 1973). A

better definition of particle size has allowed better recommendations regarding the particle

size required to optimize poultry and swine performance.

27

The effects of particle size on nutrient digestibility and live performance of poultry

and swine have been studied by several groups (Wondra et al., 1995; Fastinger and Mahan,

2003; Parsons et al., 2006), but the results have been contradictory. Parsons et al. (2006)

reported a decrease in digesta passage rate and increase in nitrogen retention when the

particle size of corn was increased. In addition, Favero et al. (2012) reported an improvement

in total tract apparent digestibility of dry matter, nitrogen, and crude fiber as the particle size

of corn was increased from 380 µm to 606 and 806 µm. On the other hand, Wondra et al.

(1995) reported a lineal increase in the fecal digestibility of dry matter, nitrogen, and gross

energy when the particle size of corn was decreased.

The results of the previous studies suggested that the response to different particle

sizes of feed ingredients differ depending on the species, age, and feed form. Poultry have

been reported to require large particles of cereal grains that can stimulate gizzard

development and reverse peristalsis in order to compensate for a short intestine (Nir et al.,

1994). Reverse peristalsis has been reported to be important to increase the exposure of the

intestinal digesta to enzymatic secretions in order to improve digestion in the upper and

lower section of the gastrointestinal tract (Duke, 1992; Nir et al., 1995). The gizzard has been

the organ that regulated intestinal motility as influenced by particle size of the feed

ingredients (Nir et al., 1995). Conversely, the growth performance of swine has been

improved as the proportions of dietary fine feed particles were fed (Steinhart, 2012).

Research had shown that when particle size was reduced from 1000 microns to 400 µm there

was an improvement in swine feed efficiency of approximately 1.3% for every 100-µm

reduction in particle size (Wondra et al., 1995; Hancock and Behnke, 2001).

28

1.7. HYPOTHESES AND RESEARCH OBJECTIVES

Feed costs represents 65 to 75% of total livestock production costs (Goodband, 2002).

Because corn usage for ethanol production has increased by 82% from 2000 to 2008, the

availability of DDGS as a feed ingredient has increased accordingly (Shurson, 2003; Schmidt

et al., 2012). During this period, the potential of DDGS to be used as a source of protein,

energy, and phosphorus to replace more expensive ingredients, such as corn, SBM, and

dicalcium phosphate in poultry and swine diets has increased tremendously (Hoffman and

Baker, 2011). However, the nutrient content of DDGS varies considerably among ethanol

plants, with crude fiber, acid detergent fiber (ADF), neutral-detergent fiber (NDF), ash,

phosphorus, and heat sensitive essential amino acids being the nutrients with the highest

variation (Speihs et al., 2002; Belyea et al., 2004; Batal and Dale, 2006; Fastinger et al.,

2006; Fiene et al., 2006; Parsons et al., 2006; Liu, 2008). Lysine has been defined as the first

and second limiting amino acid in swine and poultry diets, respectively, and has been a major

concern when a high dietary inclusion level of DDGS is used (Noll et al., 2007b). The

digestibility of lysine in DDGS has been reported to be lower than in corn and SBM (Batal

and Dale, 2006). During the drying process of DDGS the epsilon amino group of lysine has

been reported to react with the carbonyl group of reducing sugars and be rendered

unavailable (McGinnis and Evans, 1947; Warnick and Anderson, 1968; Cromwell et al.,

1993; Pahm et al., 2008a). Fastinger and Mahan (2005) reported DDGS to have an apparent

ileal digestibility of lysine of only 27%, indicating that some commercial sources of DDGS

might be severely over-heated.

The effects of particle size on nutrient digestibility and live performance of poultry

29

and swine have been studied by several groups in recent years (Wondra et al., 1995;

Fastinger and Mahan, 2003; Parsons et al., 2006), but the results have been somewhat

contradictory. While poultry species require large particles of cereal grains to stimulate

gizzard development and reverse peristalsis, swine require small particles to increase the

surface area of contact between digesta and digestive enzymes and thus increase nutrient

digestibility (Goodband et al., 2002). This apparent paradox provides an interesting subject

of research study.

Therefore, our working hypothesis was that the dietary inclusion level of DDGS in

broilers and pigs diets depends upon formulation strategies and particle size manipulation

and could be used to influence pellet durability, nutrient digestibility, and overall

performance of poultry and swine. To accomplish our working hypothesis, our research

objectives were divided into four specific hypotheses described below.

CHAPTER 2

Specific hypothesis 1. Further grinding of SBM and DDGS will improve pellet quality.

Objective 1. To evaluate the effect of further grinding of SBM on pellet quality in

finisher diets for swine.

Objective 2. To evaluate the effects of further grinding DDGS on pellet quality in

finisher diets for swine.

CHAPTER 3

Specific hypothesis 2. Broiler diets can contain up to 30% DDGS if pellet quality is

controlled closely and diets are formulated on a digestible amino acid basis.

30

Objective 1. To evaluate the effect of further grinding DDGS on pellet quality and

broiler live performance when the mixer-added fat is kept constant.

Objective 2. To determine the effect of DDGS inclusion on broiler performance in

diets formulated on a digestible amino acid basis.

Objective 3. To determine the effect percentage fines in the feed on broiler

performance.

CHAPTER 4

Specific hypothesis 3. In diets formulated on a total amino acid basis, the live performance

of broilers decreases and footpad lesions increase as dietary inclusion level of DDGS

increases.

Objective 1. To evaluate the effect of dietary DDGS inclusion level on pellet quality

when supplemental fat is added in the mixer.

Objective 2. To evaluate the effect of method of DDGS fat analysis (ether extract

versus ether extract with acid hydrolysis pretreatment) on pellet quality and broiler

live performance.

Objective 3. To evaluate the effect of dietary DDGS inclusion level on broiler growth

performance when diets are formulated on a total amino acid basis.

Objective 4. To evaluate the effect of dietary DDGS inclusion level on nutrient

digestibility and incidence of footpad lesions.

31

CHAPTER 5

Specific hypothesis 4. Further grinding of SBM and DDGS and pelleted feed without fines

improves pig live performance.

Objective 1. To evaluate the effect of further grinding SBM and DDGS on pig live

performance.

Objective 2. To evaluate the effect of percentage feed fines on pig performance.

32

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47

CHAPTER II

EFFECT OF FURTHER GRINDING DDGS AND SBM ON PELLET QUALITY IN

SWINE DIETS

48

2.1. ABSTRACT

The objective of the study was to evaluate the effect of further grinding of major feed

ingredients on pellet quality in swine finisher diets. Feed was produced at the NC State

University Feed Mill Educational Unit. Corn-soy diets contained 69.4% corn, 22.3% soybean

meal (SBM), and 6.5% poultry fat. Diets containing corn Distillers dried grains with solubles

(DDGS) were comprised of 53% corn, 30% DDGS, 8.0% SBM, and 6.5% poultry fat. Of the

6.5% poultry fat in each diet, 1.5% was added in the mixer and 5.0% was added post-

pelleting. Six dietary treatments consisted of two inclusion of DDGS (0% and 30%), two

particle sizes of DDGS (677 and 483 µm), and two particle sizes of SBM (1070 and 467

µm). All diets were steam conditioned for 45 seconds and a temperature of 82°C. A 4.4 mm

× 35 mm pellet die was used during pelleting. Each diet was replicated 4 times. Data were

analyzed using PROC GLM in SAS. Batch was the experimental unit. Models for pellet

durability index (PDI) and modified PDI included fixed effects of diet and time of day.

Contrasts were used to evaluate DDGS inclusion and regrinding DDGS and SBM on pellet

quality. Across all diets, average standard and modified PDI was 90.4 and 68.2%,

respectively. Diets containing DDGS exhibited greater (P≤0.05) standard and modified PDI

in comparison to diets without DDGS (1.6% and 9.5%, respectively). However, further

grinding of DDGS using a hammer mill equipped with 1.6 mm screen had no effect (P≥0.05)

on standard or modified PDI. Further grinding of SBM using a hammer mill equipped with

1.6 mm screen in diets without DDGS numerically (P≤0.07) improved standard and modified

PDI (2.3% and 5.8%, respectively). Within DDGS containing diets, further grinding of SBM

did not improve standard PDI (P=0.19), but improved (P≤0.05) modified PDI by 4.3%.

49

Across all diets, further grinding of SBM improved (P≤0.05) both standard and modified PDI

(1.5% and 4.7%, respectively). Adding 30% DDGS to corn-soy diets improved PDI when the

percentage of added fat in the mixer was maintain constant, regardless of the inclusion of

DDGS, and that further grinding of SBM improved pellet quality.

Key words: DDGS, particle size, pellet quality, soybean meal, regrinding

2.2. INTRODUCTION

Feed costs have represented about 60-70% of the total livestock production costs

(Patience et al., 1995). With increasing ethanol production into the future these costs are

expected to continue to increase correspondently. Improvement in feed efficiency has

reduced production costs and increased the economic return by reducing the amount of feed

required per unit of gain (Willems et al., 2013). According to Behnke and Beyer (2002), feed

processing offered an opportunity to reduce feed costs by increasing animal growth and

improving feed efficiency beyond simple feed nutritional value.

Pelleting technology has been used for many years as a tool to improve feed

efficiency and reduce production costs. Use of pelleted diets have resulted in better growth

performance and feed efficiency in comparison to mash diets (Stark, 1994; Wondra et al.,

1995) and pelleted diets have offered many economic, physical, and nutritional benefits. The

physical benefits of pelleting feed include reduced ingredient segregation during

transportation and storage and increased bulk density. Skoch et al. (1983) suggested that

pelleted feed was more palatable and reported improved feed efficiency and energy

digestibility as compared to mash diets. In addition, pelleting has allowed the inclusion of

50

ingredients with poor flowability characteristics (Stark, 2012). Poultry and swine have been

reported to consume pelleted feed in a shorter amount of time than mash feed. Chicks fed

pelleted diets spent around 5% of their times eating at the feeder as compared to 15% for

chicks fed mash diets (Behnke and Beyer, 2002). The nutritional benefits of pelleting have

been associated with increased protein digestibility by providing heat, moisture, and shear

that results in protein unfolding and partial denaturation of native structures, thus exposing

peptides linkages to enzymatic attack by endogenous proteases (Voragen et al., 1995).

According to Behnke (2001), the major factors affecting pellet quality include diet

composition (40%), particle size (20%), conditioning temperature (20%), die specification

(15%), and cooling (5%). Stark (2011) considered feed throughput as an additional factor

that affects pellet quality. Nevertheless, diet composition is considered the most dominant

single factor that influences pellet quality. The addition of fat prior to pelleting has been

reported to reduce pellet quality (Cavalcanti and Behnke, 2005a, 2005b; Fahrenholz, 2012).

In contrast, high levels of raw undenatured protein improves particle binding and pellet

quality (Briggs et al., 1999). Loar et al. (2010) showed that increasing the dietary inclusion of

DDGS reduced pellet quality. The authors reported a pellet durability of 74, 67, and 62% and

percentage fines of 31, 42, and 54% with 0, 15, and 30% DDGS, respectively.

Particle size manipulation has been an important mechanical process used to

improved pellet quality and the nutritional value of grains and other feed ingredients. Small

particle size has better particle size distribution and less segregation during mixing than

coarser particles, and it has resulted in superior pellet durability and overall growth

performance in pigs (McEllhiney, 1992; Wondra et al., 1995; Laurinen et al., 2000; Lahaye

51

et al., 2004). The increased surface area associated with particle size reduction has been

reported to enhance moisture and heat penetration to the core of the feed particle during feed

conditioning, increased starch gelatinization on the surface of the pellets, and formation of

highly durable pellets (Reimer, 1992; Dozier, 2001). Wondra et al. (1995) reported an

improvement in pellet quality from 78.8 to 86.4% as corn particle size was reduced from

1,000 to 400 microns. In general, particle size reduction of corn and other cereal grains has

been shown to improve feed efficiency in swine diets (Fastinger and Mahan, 2003).

However, there is scarce information regarding the effect of particle size of other feed

ingredients, such as SBM and DDGS, on pellet quality. The objective of this study was to

evaluate two dietary inclusion levels of DDGS (0 and 30%) at two particle sizes (677 and

482 µm) and two particle sizes of SBM (1,070 and 467 µm) on pellet quality parameters.

2.3. MATERIALS AND METHODS

2.3.1. Diets

The experimental diets consisted mainly of corn, SBM, and DDGS (Table 1). Feed

was manufactured at the North Carolina State University Feed Mill Educational Unit

(Raleigh, NC) following current Good Manufacturing Practices (GMP). The coarse DDGS

and SBM were used in the diets as received from the supplier. The fine DDGS and SBM

were obtained by grinding the coarse material using a hammermill (Model 1522, Roskamp

Champion, Waterloo, IA) equipped with a 1.6 mm screen. Dry ingredients were blended in a

counterpoise mixer (Model: TRDB126060, Hayes & Stolz, Fort Worth, TX) with 1.5%

52

added fat to follow industry practices and produce high quality pellets. The remaining fat

(5%) was added post-pelleting. Feed was steam conditioned at 82°C for 45 seconds prior to

pelleting using a 30.5 x 121.9 cm steam conditioner. Treatments were pelleted using a 30 HP

California Pellet Mill (Model PM1112-2, California Pellet Mill Co., Crawfordsville, IN)

equipped with a 4.4 mm x 35 mm pellet die. Pellets were cooled using a counter flow cooler

(Model VK09x09KL, Geelen Counterflow USA Inc., Orlando, Florida).

2.3.2. Data Collection and Laboratory Analyses

Dry sieving according to ASAE method S319.3 (ASABE, 2007) was used to

determine the particle size of the coarse and fine DDGS and SBM with the addition of sieve

agitators and 0.5 g of dispersing agent per 100 g of sample. The particle size distribution of

the coarse and fine DDGS and SBM are shown in Figures 1 and 2, respectively. Production

rate, conditioning temperature, and hot pellet temperature were monitored during pelleting

(Table 2). Hot pellet temperature was evaluated to measure the amount of frictional heat

gained in the die as feed passed thought it. The durability of the pellets was determined

according to the ASABE standard method S269.4 (ASABE, 2007). Approximately 3.5 kg of

sample were collected for each batch of feed (227 kg) at evenly spaced intervals upon

discharge from the pellet mill and cooled immediately by placing the sample of hot pellets

into cooling trays at a depth of approximately 1 cm and then cooled with ambient air using a

counter flow pellet cooler. The tumble box method was used to calculate the pellet durability

index (PDI) in accordance with the ASAE standard method. Four sub-samples of pellets were

screened using a US #6 sieve (3.35 mm) to remove the fines produced during the pelleting

53

process and 500 g of each placed into 1 of the 4 compartments of the tumble box. For the

modified method, three hex nuts (50 g/nut) were added in each tumble box compartment in

order to increase the impact forces inside the tumble box and improve the ability to predict

the true pellet quality of the feed at the farm. The sub-samples were tumbled at 50 rpm for 10

min. After tumbling, each sub-sample was sifted again using the US #6 sieve to remove the

fines and the re-weighed. The PDI was calculated as the ratio of the weight of the pellets that

remained in the sieve after tumbling relative to the initial weight before tumbling (500 g) and

reported as a percentage. The compartments in the tumble box were cleaned by hand after

each PDI test in order to remove fines that accumulated in the corners.

2.3.3. Statistical Analyses

The batch of manufactured feed served as the experimental unit for statistical analysis

of the feed processing data. Data were analyzed by analysis of variance using the General

Linear Model (GLM) procedure of SAS (SAS Institute, 2006). Six dietary treatments were

used and consisted of two dietary inclusion levels of DDGS (0% and 30%), two particle sizes

of DDGS (677 and 483 µm), and two particle sizes of SBM (1070 and 467 µm). Each dietary

treatment was replicated by 4 batches, with each batch representing an experimental unit

(909 kg/batch). Dietary treatments were randomly ordered within each feed processing

replication. Models for standard and modified PDI included fixed effects of diet and time of

day. Contrasts were used to evaluate DDGS inclusion level and further grinding of DDGS

and SBM on PDI. Statements of statistical differences were based upon P≤0.05, unless

otherwise indicated. Differences between means were separated by the least significant

54

difference test.

2.4. RESULTS AND DISCUSSION

Across all diets, average standard and modified PDI was 90.4 (SD = 2.15) and 68.2

(SD = 6.81), respectively. The average production rate was 849 kg/hr (SD=22) for all diets

(Table 2). Diets containing DDGS had greater (P≤0.05) modified PDI in comparison to diets

without DDGS (71.38 versus 61.38%). Wang et al. (2007) reported that broiler diets

containing 15% DDGS had similar visually apparent quality as compared to control corn-

SBM diets, but the diets containing 30% DDGS appeared to have lower pellet quality with

higher percentage fines. Loar et al. (2010) reported a decreased standard PDI from 74.4 to

66.8 and 62.1% and a decreased modified PDI from 56.3 to 43.5 and 34.1% when DDGS

were included at 15 and 30% of the diet as compared to the corn-SBM control diet. Similarly,

Min et al. (2008) reported a linear increase in the percentage of fines as the dietary inclusion

level of DDGS was increased from 0 to 15 and 30%, particularly in the finisher feeds, that

were made with a pellet die having bigger diameter holes than the starter diet (4.76 versus

2.38 mm). The increased percentage of fines was expected as more poultry oil was added to

the DDGS-containing diets in order to maintain a caloric equivalency among diets. Wang et

al. (2008) reported less variation in percentage fines as the dietary inclusion level of DDGS

increased when the percentage fat in the mixer was kept constant. Supplemental fat has been

reported to impair pellet binding by inhibiting the penetration of steam into the core of feed

particles and by reducing the friction between the die wall and feed ingredients (Thomas and

van der Poel, 1996; Briggs et al., 1999; Rollins, 2002; Cavalcanti and Behnke, 2005b;

55

Fahrenholz, 2012). In our study, we maintained added fat in the mixer at 1.5%, regardless of

the DDGS inclusion level. Stender and Honeyman (2008) reported a decrease in PDI from

78.9 to 47.4% as DDGS was increased from 0 to 40% in swine diets. In contrast, Fahrenholz

(2008) studied the effect of adding 0, 10, 20, 30, and 40% DDGS and reported that dietary

DDGS inclusion level had no effect on either standard or modified PDI, but increasing the

inclusion of DDGS to 40% resulted in a 10% decrease in the pelleting production rate as

compared to the corn-SBM control. In contrast, Feoli (2008) reported an improvement in PDI

from 88.5 to 93.0% in diets containing 30% DDGS as compared to the corn-SBM control

diet.

The dietary inclusion level of DDGS did not affect feed production rate in this

experiment (Table 4). However, diets that contained 30% DDGS had a higher increment in

die frictional heat (P≤0.05) than the control corn-SBM diet. In order to maintain similar

available phosphorus contents among all diets, diets containing 30% DDGS did not include

defluorinated phosphate as compared to the 0.53% defluorinated phosphate included in the

diets without DDGS. Defluorinated phosphate is abrasive and keeps the surface of the die

polished, thereby minimizing frictional resistance as mash passes through the die and

increase pellet production rate. Behnke (1981) reported >20% increased pellet mill

throughput at similar motor load when either coarse or fine deflourinated phosphate replaced

similar amount of monocalcium phosphate, which is not as abrasive.

Further grinding of DDGS had no effect (P≥0.05) on the standard or modified PDIs.

The particle size distribution between the coarse and the fine ground DDGS (Figure 2)

overlapped to a greater extent than the particle size distribution of the coarse and fine SBM

56

(Figure 1). Fahrenholz (2008) reported that regrinding previously pelleted DDGS increased

standard and modified PDI. Further grinding DDGS at the feed mill decreased the particle

size 194 µm as compared to the DDGS as received (677 versus 483 µm). Several researchers

observed increased PDI and decreased percentage pellet fines as the particle grind size of

cereal grains included in the feed was reduced (McEllhiney, 1992; Stark, 1994; Wondra et

al., 1995; Chewning, 2010), likely due to increased surface area and more contact points per

unit of volume within the pellet matrix (Behnke, 2001). Moreover, heat and moisture may

penetrate more quickly to the center of smaller particles than larger ones during conditioning.

According to Dozier (2001), the particle size of corn-SBM diets fed to broilers should be

approximately 650-700 µm in order to obtain good pellet quality, while particles larger than

1,000 or 1500 µm have been associated with an increase in the number of fracture points

(Franke, 2006). Muramatsu et al. (2013) reported an increase in PDI from 74.6 to 77.3%

when the average particle size of the whole diet was decreased from 1,041 to 743 µm.

Further grinding of SBM in diets without DDGS tended (P≤0.07) to improve standard

and modified PDIs (2.3% and 5.8%, respectively). Pacheco (2011) reported improvements in

pellet quality of 10 and 13% when solvent extracted and expeller extracted SBM was ground

in corn-SBM diets. Proteins derived from cereal grains with dough-forming capabilities such

as rye, barley, and wheat (Moran, 1989; Winowiski, 2006) and SBM (Cavalcanti, 2004) have

been reported to improve pellet durability. Within diets that contained DDGS, regrinding

SBM did not improve (P=0.19) standard PDI, but improved (P≤0.05) modified PDI by 4.3%.

Across all diets, further grinding of SBM improved (P≤0.05) both standard and modified

PDIs (1.5% and 4.7%, respectively). Further grinding of SBM may have increased the

57

surface area of the SBM protein for pellet binding and overall PDI. Adding 30% DDGS to

corn-SBM diets improved PDI when the amount of added fat in the mixer was kept constant.

In addition, further grinding of SBM improved PDI in diets with or without DDGS.

58

2.5 TABLES AND FIGURES

Table 1. Composition and calculated contents of the experimental diets (% as fed basis)

Item

Dietary DDGS Inclusion Level

0% 30%

Ingredient ———————— (% of diets) ———————— Corn 69.41 52.99

Soybean meal, 48% CP — 8.05

DDGS 22.30 30.00

Deflourinated phosphate, 18.5% P 0.53 —

Poultry fat 6.50 6.50

Limestone 0.85 1.69

Salt 0.30 0.35

L-Threonine — 0.01

L-Lysine-HCl, 78% — 0.30

Vitamin premix1 0.02 0.02

Mineral premix2 0.05 0.05

Selenium premix3 0.03 0.03

Stafac 204 0.01 0.01

Phytase 0.01 0.01

Calculated nutrients

Metabolizable energy, kcal/g 3.61 3.52

Crude protein, % 15.91 15.74

Crude fat, % 9.24 10.96

Calcium, % 0.57 0.69

Available phosphorus, % 0.24 0.28

Lysine, % 0.82 0.87

Methionine, % 0.27 0.29

Methionine + Cysteine, % 0.54 0.58

Threonine, % 0.61 0.59

Tryptophan, % 0.18 0.15 1 Vitamin premix provided the following per kg of diet: 6171 IU of vitamin A, 880 IU of vitamin D, 35 IU of vitamin E,

0.02 mg/kg of vitamin B12, 0.18 mg/kg of biotin, 2.91 mg/kg of vitamin K, 4.40 mg/kg of riboflavin, 17.64 mg/kg of

pantothenic acid, 26.45 mg/kg of niacin, 1.32 mg/kg of folate. 2 Mineral premix provided the following per kg of diet: 16.5 mg/kg of Cu, 165.3 mg/kg of Fe, 39.60 mg/kg of Mn, 165.30

mg/kg of Zn, 0.30 mg/kg of I, 0.30 mg/kg of Se. 3 Selenium premix provided 0.2 mg/kg Se. 4 Virginiamycin was included at 5.5 mg/kg (Stafac 20, Phibro Animal Health Corporation, Ridgefield Park, NJ, USA).

59

Table 2. Descriptive statistics of the experimental diet

Item No. of batches Mean Standard deviation

Feed production rate, kg/hour 24 849.0 22.0

Conditioning temperature, °C 24 82.3 1.6

Hot pellet temperature, °C 24 85.8 1.9

Standard pellet durability index, % 24 90.4 2.1

Modified pellet durability index, % 24 68.2 6.8

60

Table 3. Particle size distribution of corn, soybean meal, and DDGS

Treatment

Corn Coarse SBM1 Fine SBM Coarse DDGS2 Fine DDGS

U. S. Sieve Sieve Size Actual Cum3 Actual Cum Actual Cum Actual Cum Actual Cum

# µm % % % % % % % % % %

4 4760 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

6 3360 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

8 2380 0.0 0.0 3.7 3.7 0.0 0.0 0.0 0.0 0.0 0.0

12 1680 0.5 0.5 18.2 21.9 0.0 0.0 1.5 1.5 0.0 0.0

16 1190 7.0 7.5 30.9 52.8 1.2 1.2 14.1 15.6 0.4 0.4

20 840 13.2 20.7 20.0 72.8 16.1 17.3 22.7 38.2 11.5 11.9

30 590 15.4 36.1 13.5 86.2 28.3 45.6 25.3 63.5 30.4 42.3

40 420 15.2 51.4 7.2 93.4 22.6 68.2 20.3 83.8 27.7 70.0

50 297 11.3 62.6 3.2 96.6 12.4 80.6 9.3 93.1 14.8 84.8

70 210 8.9 71.6 1.1 97.7 6.5 87.1 2.8 95.9 6.4 91.2

100 149 5.8 77.4 0.6 98.3 4.5 91.6 1.7 97.6 3.5 94.7

140 105 6.0 83.3 0.4 98.7 3.3 95.0 0.9 98.5 2.3 97.0

200 74 10.2 93.5 0.3 99.0 1.7 96.6 0.4 98.9 1.1 98.1

270 53 3.4 97.0 0.3 99.4 1.2 97.9 0.5 99.4 1.2 99.3

Pan 37 3.0 100.0 0.6 100.0 2.1 100.0 0.6 100.0 0.7 100.0

Average, µm 355.0 1070.0 467.0 677.0 483.0

SD 2.6 1.9 2.0 1.8 1.81 1 SBM = Soybean meal 2 DDGS = Distillers Dried Grains with Solubles 3 Cum = Cumulative

61

Table 4. Effect of particle size and inclusion of DDGS on pellet durability index (PDI) and feed production rate

a-b Means with different superscripts in the same column differ significantly (P ≤ 0.05).

A-B Means with different superscripts in the same column differ significantly (P ≤ 0.01).

1 DDGS as received had a particle size of 677 µm and 483 µm after grinding using a hammer mill equipped with a 1.6 mm screen

2 SBM as received had a particle size of 1,070 µm and 467 µm after grinding using a hammer mill equipped with a 1.6 mm screen

3 Standard PDI = (weight of fines/weight of initial sample) x 100 after tumbling 500 g of whole pellet at 50 rpm for 10 min

4 Modified PDI = (weight of fines/weight of initial sample) x 100 after tumbling 500 g of whole pellet at 50 rpm for 10 min with the addition of 3 hex nuts (50g/nut)

5 Increase in temperature due to frictional forces as feed moves through the pellet die during the pelleting process

DDGS DDGS

Particle Size1 SBM

Particle Size2

PDI Production

Rate

Conditioning

Temperature

Hot Pellet

Temperature

Die

Friction5

Standard3 Modified4

————— (%) ————— —— (µm) —— —— (µm) —— ——— (%) —— — (kg/hr) — — (F) — — (F) — — (F) —

0 89.4 61.9B 852 180.4 185.4 5.0B

30 90.9 71.4A 847 179.9 186.9 7.0A

SEM 0.7 1.8 3 0.6 0.6 0.7

677 91.6 72.5 847 180.3 186.9 6.6

483 90.3 70.3 847 179.6 187.0 7.4

SEM 0.5 1.3 4 0.4 0.7 0.7

30 1070 90.4 69.3B 849 179.9 186.8 6.9

30 467 91.5 73.5A 845 180.0 187.1 7.1

SEM 0.5 1.3 4 0.4 0.7 0.7

0 1070 88.3 59.0 851 181.3 185.0 3.8

0 467 90.5 64.8 854 179.5 185.8 6.3

SEM 1.4 3.2 6 1.2 0.9 0.9

30 677 1070 91.3 71.5 850 180.0 187.3 7.3

30 677 467 92.0 73.5 845 180.5 186.5 6.0

30 483 1070 89.5 67.0 848 179.8 186.3 6.5

30 483 467 91.0 73.5 846 179.5 187.8 8.3

SEM 0.7 1.9 5 0.6 1.0 0.9

Source of variation ——————————————————— P-value ————————————————

DDGS Inclusion 0.093 0.001 0.221 0.543 0.060 0.031

Soybean meal particle size - 0% DDGS 0.302 0.060 0.787 0.323 0.589 0.111

DDGS particle size - 30% DDGS 0.064 0.248 0.921 0.337 0.900 0.441

Soybean meal particle size - 30% DDGS 0.121 0.041 0.532 0.845 0.706 0.795

DDGS x soybean meal particle size - 30% DDGS 0.588 0.248 0.817 0.560 0.269 0.137

62

Figure 1. Average particle size and particle size distribution of soybean meal used in swine


hammermill equipped with a 1.6 mm screen.

63

Figure 2. Average particle size and particle size distribution of DDGS used in swine


hammermill equipped with a 1.6 mm screen.

64

2.6. REFERENCES

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Sieving. Am. Soc. Agric. Eng., St. Joseph, MI.

ASABE. 2007. Cubes, Pellets and Crumbles-Definitions and Methods for Determining

Density, Durability, and Moisture Content. Am. Soc. Agric. Eng. St. Joseph, MI.

Behnke, K. C. 1981. Pellet mill performance as affected by mineral source. Feedstuffs.

53:34-36.

Behnke, K. C. 2001. Factors influencing pellet quality. Feed Technol. 5:19-22.

Behnke, K. C., and R. S. Beyer. 2002. Effect of feed processing on broiler performance. Intl.

Seminar Poult. Prod. and Pathol. Santiago, Chile.

Briggs, J. L., D. E. Maier, B. A. Watkins, and K. C. Behnke. 1999. Effects of ingredients and

processing parameters on pellet quality. Poult. Sci. 78:1464-1471.

Cavalcanti, W. B. 2004. The effect of ingredient composition on the physical quality of

pelleted feeds: a mixture experimental approach. Ph.D. Dissertation, Kansas State

University, Manhattan, KS.

Cavalcanti, W. B. and K. C. Behnke. 2005a. Effect of composition of feed model systems on

pellet quality: mixture experimental approach. I. Cereal Chem. 82:455-461.

Cavalcanti, W. B., and K. C. Behnke. 2005b. Effect of composition of feed model systems on

pellet quality: mixture experimental approach. II. Cereal Chem. 82:462-467.

Chewning, C. G. 2010. Evaluation of post pellet liquid application, particle size, and feed

form on broiler performance. M.S. Thesis. North Carolina State University, Raleigh,

NC.

Dozier, W. A. 2001. Cost effective pellet quality for meat birds. Feed Management. 52:1-3.

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Fahrenholz, A. C. 2008. The effects of DDGS inclusion on pellet quality and pellet mill


Fahrenholz A. C. 2012. Evaluating factors affecting pellet durability and energy consumption

in a pilot feed mill and comparing methods for evaluating pellet durability. Ph.D.

Dissertation, Kansas State University, Manhattan, KS.

Feoli, C. 2008. Use of corn- and sorghum-based distillers dried grains with solubles in diets

for nursery and finishing pigs. Ph.D. Dissertation, Kansas State University,

Manhattan, KS.

Fastinger, N. D., and D. C. Mahan. 2003. Effect of soybean meal particle size on amino acid

and energy digestibility in grower-finisher swine. J. Anim. Sci. 81:697-704.

Franke, M., and A. Rey. 2006. Improving pellet quality and efficiency. Feed Tech. 10:12-15.

Lahaye, L., P. Ganier, J. N. Thibault, and B. Seve. 2004. Technological processes of feed

manufacturing affect protein endogenous losses and amino acid availability for body

protein deposition in pigs. Anim. Feed Sci. Technol. 113:141-156.

Laurinen, P., H. Siljander-Rasi, J. Karhunen, T. Alaviuhkola, M. Nasi, and K. Tuppi. 2000.

Effects of different grinding methods and particle size of barley and wheat on pig

performance and digestibility. Anim. Feed Sci. Technol. 83:1-16.


dried grains with solubles to broilers from 0 to 28 days post hatch on broiler


Poult. Sci. 89:2242-2250.

McEllhiney, R. 1992. What is the optimum particle size for pelleting? Feed Management

46:9-19.

Min, Y. N., F. Z. Liu, Z. Wang, C. Coto, S. Cerrate, F. P. Costa, F. Yan, and P. W.

Waldroup. 2008. Evaluation of distillers dried grains with solubles in combination

with glycerin in broiler diets. Intl. J. Poult. Sci. 7:646-654.

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Moran, E. T. 1989. Effect of pellet quality on the performance of meat birds. Pages 87-108 in

Recent Advances in Animal Nutrition. Haresign, W., and D. J. Cole, Eds.

Butterworths Publishing, London, England.

Muramatsu, K., A. Maiorka, I. C. Mores, R. N. Reis, F. Dahlke, A. A. Pinto, U. A. Dias, M.

Bueno, and M. Imagawa. 2013. Impact of particle size, thermal processing, fat

inclusion and moisture addition on pellet quality and protein solubility of broiler

feeds. J. Agric. Sci. Technol. 3:1017-1028.

Pacheco, W. J. 2011. Evaluation of trypsin inhibitors levels and particle size of expeller-

extracted soybean meal on broiler performance. M.S. Thesis. North Carolina State

University, Raleigh, NC.

Patience, J. F., P. Thacker, and C. F. M. de Lange. 1995. Swine Nutrition Guide 2nd

ed.

Prairie Swine Centre Inc., Univ. of Saskatchewan, Saskatoon, Canada.

Reimer, L. 1992. Conditioning. In: Proc. Northern Crops Institute Feed Mill Management

and Feed Manufacturing Technol. Short Course. California Pellet Mill Co.

Crawfordsville, IN.

Rollins, D. 2002. The pelleting process. Arkansas Poult. Symp., Fayetteville, AR.

SAS. 2006. SAS/STAT User's guide, SAS Institute, Inc., SAS Press, Cary, NC.

Skoch, E. R., S. F. Binder, C. W. Deyoe, G. L. Allee, and K. C. Behnke. 1983. Effects of

pelleting conditions on performance of pigs fed a corn-soybean meal diet. J. Anim.

Sci. 57:922-928.

Stark, C. R. 1994. Pellet quality I. Pellet quality and its effects on swine performance. Ph.D.

Dissertation, Kansas State University, Manhattan.

Stark, C. R. 2011. Feed processing to maximize feed efficiency. Pages 131-151 in Feed

Efficiency in Swine. Patience, J. F. Ed. Wageningen Academic Publisher.

Netherlands.

67

Stark, C. R. 2012. Feed processing to improve poultry performance. Arkansas Nutrition

Conference. Rogers, AR.

Stender, D. and M. S. Honeyman. 2008. Feeding pelleted DDGS-based diets to finishing pigs

in deep-bedded hoop barns. J. Anim. Sci. 86 (Suppl. 3):84.

Thomas, M., and A. F. B. van der Poel. 1996. Physical quality of pelleted animal feed. 1.

Criteria for pellet quality. Anim. Feed Sci. Technol. 61:89-112.

Voragen, A. G., H. Gruppen, G. J. Marsman, and A. J. Mul. 1995. Effect of some

manufacturing technologies on chemical, physical, and nutritional properties of feed.

Pages 93-126 in Recent Advances in Animal Nutrition. Feed Manufacturers Conf.,

Nottingham University Press. Nottingham, UK.


increasing levels of distillers dried grains with solubles (DDGS) in broiler diets. Int. J.

Poult. Sci. 6:501-507.


2008. Evaluation of corn distillers dried grains with solubles in broiler diets


density with constant 1% fat. Int. J. Poult. Sci. 7:630-637.

Willems, O. W., S. P. Miller, and B. J. Wood. 2013. Aspects of selection for feed efficiency

in meat producing poultry. World's Poult. Sci. J. 69:77-87.

Winowiski, T. 1988. Wheat and pellet quality. Feed Management 39:58-64.

Wondra, K. J., J. D. Hancock, K. C. Behnke, R. H. Hines, and C. R. Stark. 1995. Effect of

particle size and pelleting on growth performance, nutrient digestibility, and stomach

morphology in finishing pigs. J. Anim. Sci. 73:757-763.

68

CHAPTER III

EFFECT OF PARTICLE SIZE, DDGS INCLUSION, AND PELLET QUALITY ON

BROILER LIVE PERFORMANCE AND GASTROINTESTINAL DEVELOPMENT

69

3.1. ABSTRACT

Previous research has shown that one of the main limitations of DDGS inclusion in poultry

diets was the reduction in pellet quality. Researchers have also shown that coarse feed

ingredients particles could alter GIT development, nutrient digestion, and overall poultry

performance. The objective of this study was to evaluate the effect of particle size and

inclusion level of DDGS on pellet quality, organ development, nutrient digestibility, and

broiler live performance. A total of 2,304 male broilers were randomly distributed among 12

treatments with 6 replicate pens per treatment, which constituted a 2x2x3 factorial

arrangement of 2 DDGS particle grind sizes (coarse grind-745 and fine grind-482 µm), 2

DDGS inclusion levels (15 and 30%), and 3 levels of fines in the finished feed (0, 25, and

50%). The starter diets were fed in crumbled form and the grower diets were fed in pelleted

form. Feed consumption and BW were determined at 14, 35, and 42 d of age and feed

conversion ratio (FCR) calculated by including the BW of all dead birds. At 42 d, gizzard

and proventriculus were collected to determine their relative weights. Particle size and pellet

quality had an effect on BW. Birds fed fine DDGS had a greater feed intake (P≤0.05) and

higher BW (P≤0.05) at 42 d than birds fed coarse DDGS, with no difference in FCR. Birds

fed diets with no fines exhibited greater BW at 35 and 42 d than birds fed diets with 50%

fines (P≤0.05). Birds fed 30% DDGS exhibited greater feed consumption (P≤0.05) but

poorer FCR (P≤0.05) at 42 d than birds fed 15% DDGS. Birds fed 30% DDGS possessed

greater proventriculus weight (P≤0.05) than birds fed 15% DDGS. Birds fed coarse DDGS

(745 µm) had greater gizzard weight (P≤0.05) than birds fed fine DDGS (482 µm). The

70

results of this experiment demonstrated that birds performed better when fed fine ground

DDGS (482 µm) with no fines in the feed.

Key words: DDGS, particle size, fines, gizzard, proventriculus

3.2. INTRODUCTION

High global feed prices has forced nutritionists to search for low cost feed ingredients

as feed has accounted for around 60-70% of total production costs in the U.S. poultry

industry (Coon, 2002). In addition, the increased usage of corn as a raw material for ethanol

production has led to an increased supply of distillers dried grains with solubles (DDGS)

(Noll et al., 2007). DDGS have become a source of protein, energy, and phosphorus

(Martinez Amezcua et al., 2004) that has replaced more costly feed ingredients as its price

has declined into a favorable range for many different types of livestock and poultry

(Hoffman and Baker, 2010). For diets formulated on a total amino acid basis, Lumpkins et al.

(2004) reported that up to 6% DDGS could be used in starter diets and 12-15% in grower and

finisher diets without adverse effects on live performance. However, Shim et al. (2011)

conducted an experiment in which diets were formulated on a digestible amino acid basis and

reported no significant differences in BW gain, FCR, and mortality at 42 d of age in diets that

contained 0, 8, 16, or 24% DDGS.

Previous research has also shown that the main constraints of DDGS usage in poultry

diets were nutrient variability, particularly lysine and mineral content (Cromwell et al., 1993;

Spiehs et al., 2002), caking during transportation that caused flowability problems at feed

mills, and reduced pellet quality (Min et al., 2008; Stender and Honeyman, 2008).

71

Improvements in pellet quality has increased bulk density, improved flowability, and allowed

the inclusion of ingredients with poor flowability characteristics (Stark, 2012). In addition,

feed with high pellet quality has been reported to increase feed intake (Nir et al., 1995;

Chewning, 2010), improve FCR (Amerah et al., 2008), and improve overall broiler live

performance. Thus, pellet quality must be considered in order to guarantee optimum broiler

live performance (Briggs et al., 1999). According to Behnke (1994), the main factors that

have influenced pellet quality have been feed formulation, conditioning temperature, die

specification, cooling, and particle size.

Previous research with cereal grains and proteins meals have shown the importance of

large feed particle size on nutrient digestibility (Pacheco et al., 2013), mineral utilization

(Kilburn and Edwards, 2004), organ development (Jacobs et al., 2010; Amerah et al., 2007),

and overall poultry performance. Other authors have shown a decrease proventricular

swelling and better compartmentalization between gizzard and proventriculus when large

particles were included in the feed. (Jones and Taylor, 2001). However, currently there is a

lack of information regarding the effect of particle size of DDGS on broiler live performance.

This study was designed to evaluate the effect of particle size, DDGS inclusion, and pellet

quality on nutrient digestibility, gizzard and proventriculus weight, and broiler live

performance.

72


3.3.1. DDGS Analyses

DDGS were obtained from a local elevator in Selma, NC and were analyzed for ether

extract after acid hydrolysis (method 954.02), crude protein (N x 6.25) (method 990.03), and

crude fiber (method 962.09; AOAC, 2006) prior to feed formulation (Table 1). Dry sieving

according to ASAE method S319.3 (ASABE, 2007) was used to determine the particle size

of DDGS with the addition of sieve agitators and 0.5 g of dispersing agent per 100 g of

sample.

3.3.2. Diets

Starter and grower diets (Table 2) were composed mainly of corn, SBM, and DDGS

and were formulated to meet or exceed suggested minimum requirements of Ross 708

broilers (Aviagen, 2007) and were formulated on a digestible amino acids basis. Amino acid

digestibility coefficients for DDGS were based on values reported by Batal and Dale (2006)

and Fiene et al. (2006). The grower diet contained 0.5% titanium dioxide, which was used as

an indigestible marker for determination of nutrient digestibility. Feed was produced at the

North Carolina State University Feed Mill Educational Unit (Raleigh, NC) following current

Good Manufacturing Practices (GMP). The coarse DDGS was used in the diets as received

from the supplier. The fine ground DDGS was obtained by grinding the coarse DDGS using

a hammermill (Model 1522, Roskamp Champion, Waterloo, IA) equipped with a 1.6 mm

screen. Dry ingredients were blended in a counterpoise mixer (Model TRDB126060, Hayes

& Stolz, Fort Worth, TX) with 1% added fat in order to produce high quality pellets with

73

fewer fines. Mash diets were conditioned at 85°C for 45 seconds and then pelleted using a

pellet mill (Model PM1112-2, California Pellet Mill Co., Crawfordsville, IN) equipped with

a 4.4 mm x 35 mm die. Pellets were cooled using a counter flow cooler (Model VK09x09KL,

Geelen Counterflow USA Inc., Orlando, Florida). The fines produced during the pelleting

process were separated using feed screeners and were analyzed to ascertain that they had the

same nutritional composition as the pellets. Variable levels of pellets, fines, and remaining

fat were mixed using a 227 kg double ribbon mixer (Model SRM 304, Scott Equipment Co.,

New Prague, MN) to accomplish the desired percentage of fines in the final feed.

3.3.3. Bird Husbandry

The care of the birds used in this trial conformed to the Guide for Care and Use of

Animals in Agricultural Research and Teaching (FASS, 2010). A total of 2,304 male broilers

(Ross 708, Aviagen Inc., Huntsville, AL) were obtained from the university broiler breeder

flock. Birds were hatched at the research location and reared in a curtain-sided, heated, and

fan ventilated broiler house until 42 d of age. Birds were randomly allocated with 32 chicks

per pen to 72 pens in total. Every pen (120 x 380 cm) contained one bell-type drinker and

two tube feeders and was assigned to one of 12 dietary treatments combinations with 6

replicate pens per combination. Chicks were raised on new litter and had ad libitum access to

feed and water throughout the study. Three supplemental feeder flats were used until 7 d of

age, 2 feeder flats until 10 d, and 1 feeder flat until 14 d of age. Small amounts of feed were

added twice daily to the feeder flats to guarantee appropriate feed consumption. Feed that

remained in the feeder flat at 14 d was screened and added to the tube feeders before weigh

74

back. A common starter diet that contained 6% DDGS was used to 14 d of age in order to

adapt the gastrointestinal tract (GIT) of the birds to efficiently digest DDGS and to avoid

sudden changes in the nutrition and feeding program. Chicks were provided 0.9 kg starter

feed/chick and 3.9 kg grower feed/chick. Starter diets were fed as crumbles and grower diets

were fed as 5-mm pellets. Starter feed was adjusted for mortality to provide the same

quantity of feed per bird in order to maintain a similar cumulative nutrient package across

pens. Feed additions were weighed, recorded, and added in 454 g (1 lbs.) increments per bird

alive. Feeders were shaken twice per day from 1 to 14 d and three times per day from 15 to

42 d to maintain fresh feed in front of the chicks, as well as stimulate and prevent variation in

feed intake due to feed flow characteristics. Photoperiods were 23L:1D from 1 to 7 d,

22L:2D to 14 d, 20L:4D to 21 d, and natural light from 22 to 42 d of age. High and low air

temperatures were recorded daily and stirring fans were used to maintain a consistent

temperature in the entire house. The target temperatures were 32°C from placement to 7 d,

29ºC to 14 d, 27ºC to 21 d, and ambient thereafter. High and low temperatures were recorded

twice daily.


Standard processing data such as pellet production rate and conditioning temperature,

were controlled closely during feed manufacturing. The durability of the pellets was

determined according to the American Society of Agricultural Engineers standard method

S269.4 (ASABE, 2007). Approximately 2,500 g of feed was collected and cooled

immediately upon discharge from the pellet mill and placed into cooling trays at a depth of

75

approximately 1 cm and then cooled with ambient air using a counterflow pellet cooler. The

standard tumble box method was used employing a device locally constructed and operated

in accordance with the ASAE standard.

Two sub-samples of pellets were screened using a US #6 sieve (3.35 mm) to remove

the fines produced during the pelleting process and 500 g of each was placed into 1 of the 4

compartments of the tumbling box. For the modified method three hex nuts (50 g/nut) were

added in the tumble box compartment. The sub-samples were tumbled at 50 rpm for 10 min.

After tumbling, each sub-sample was sifted again using the US #6 sieve to remove the fines

and then re-weighed. The pellet durability index was calculated as the ratio of the weight of

the pellets that remained in the sieve after tumbling relative to the initial weight before

tumbling (500 g) and reported as a percentage. The compartments in the tumbling box were

cleaned by hand after each pellet durability test in order to remove any fines that

accumulated in the corners.

Feed consumption and BW by pen were recorded at 14, 35, and 42 d of age. Mortality

was removed, weighed, and recorded twice daily. Feed conversion ratio (FCR) was

calculated by adding the BW of dead birds to the BW of live birds in each pen. Cumulative

FCR was calculated for the periods 1-14, 1-35, and 1-42 d. At 42 d gizzard, proventriculus,

and ileal samples were collected. Ileal digesta was collected (2 cm posterior of Meckel’s

diverticulum to 2 cm anterior of the ileal-cecal junction) by gently squeezing the ileal

contents in a manner that provided sufficient sample for digestibility analysis. Gizzard and

proventriculus were excised, external fat and internal contents removed, rinsed, and blotted

dry and their weights were expressed relative to BW.

76

3.3.5. Ileal Analyses

Titanium dioxide analysis was used to calculate ileal digestibility of energy, fat, and

protein (Fan et al., 1994; Marty et al., 1994). The pellets and the fines were analyzed for

gross energy (Merrill and Watt, 1973), moisture (method 934.01), ether extract after acid

hydrolysis (method 954.02), and crude protein (N x 6.25) (method 990.03, AOAC, 2006).


A pen of broilers served as the experimental unit for statistical analysis. Data were

analyzed using PROC GLM (SAS, 2006) as a randomized complete block design with a 2 x

2 x 3 factorial arrangement to identify main effects and interactions. The analysis consisted

of two particle sizes (745 and 482 µm) of DDGS, two inclusion levels (15 and 30%) of

DDGS, and three percentages of feed fines (0, 25, and 50%). Statements of statistical

differences were based upon P≤0.05 unless otherwise indicated. Differences between means

were separated by the least significant difference test.


3.4.1. Feed Manufacturing

There was a significant interaction (P≤0.01) between the particle size and the

inclusion level of DDGS on pellet durability index (PDI) (Table 3). Pellet durability was

negatively related to the proportion of DDGS and the diets that contained 15% DDGS had a

greater pellet durability (P≤0.01) as compared to diets that contained 30% DDGS at 482 and

745 µm. However, pellet durability decreased more in diets with 745 µm DDGS (5.1 versus

77

1.75%), as compared to diets that contained 482 µm DDGS, when the inclusion of DDGS

was increased from 15% to 30%. Previous authors have reported an improvement in pellet

quality as the particle size of cereal grains and SBM was decreased (Reece et al., 1986;

Wondra et al., 1995; Pacheco et al., 2013). According to Behnke (1994), small particles

increase the surface area and the number of contact points within the pellet matrix. In the

current study, grinding the DDGS from 745 µm to 482 µm resulted in reduced PDI (P≤0.01).

This was not expected, and the only explanation was that grinding the 9.8% crude fat DDGS

could have released fat from the protein matrix and thus impeded particle size agglomeration

during pelleting. Fat has been reported to function as a lubricant in the pellet die (Stark,

1994; Jones et al., 1995; Thomas et al., 1998; Cutlip et al., 2008), which may have decreased

die friction and pellet binding. Indeed, grinding the DDGS from 745 µm to 482 µm produced

a higher feed pellet production rate (P≤0.01). According to Moritz et al. (2003) die

lubrication contributed to reduce electrical energy usage and manufacturing costs required to

pellet broiler feed.

3.4.2. Broiler Live Performance

Diets that contained the higher inclusion of DDGS contained higher percentage of

crude protein (22.2 versus 21.1%), because they were formulated to maintain a minimum

digestible amino acid level. DDGS have been reported to contain a lower lysine digestibility

value than corn and SBM. During the drying process of DDGS, high temperatures are used in

order to reduce the moisture content to around 10%, which decreases transportation costs and

increases self-life (Kwiatkowski et al., 2006). However, severe heating is associated with

78

decreased protein quality and reduced digestibility of certain amino acids. The free amino

group of lysine can react with reducing sugars in the Maillard reaction in the presence of heat

to form undigestible complexes (Cromwell et al., 1993; Spiehs et al., 2002; Batal and Dale

2006; Fontaine et al., 2007). Variability in the proportion of wet cake and thin stillage added

during DDGS production also contributes to the observed variability in the digestibility of

protein and amino acids in the final DDGS (Belyea et al., 1998).

There were no significant interactions between DDGS inclusion, DDGS particle size,

and percentage of feed fines, thus only main effects were discussed below (Table 4). Birds

fed diets with 30% DDGS exhibited greater feed consumption (P≤0.05), but poorer FCR

(P≤0.05) than birds fed diets with 15% DDGS, which resulted in no significant differences in

bird BW at 42 d of age. Shim et al. (2011) reported higher feed consumption from 19 to 28 d

of age as the inclusion of DDGS was increased from 0 to 24%.

Birds fed 482-µm-DDGS had greater feed consumption (P≤0.05) and BW (P≤0.05) at

42 d of age than birds fed 745-µm-DDGS, but no differences were observed for FCR.

Previous studies have shown that coarse particles of cereal grains and protein meals altered

gastrointestinal tract (GIT) development, nutrient digestion and absorption, and overall

poultry live performance (Engberg et al., 2002; Parsons et al., 2006; Pacheco et al., 2013).

However, in this study the particle size distribution (Fig. 1) between 745 and 482 µm

overlapped significantly, which probably made it difficult to find significant differences in

FCR. Parsons et al. (2006) reported greater feed intake, but poorer FCR when birds were fed

coarse mash diets. Favero et al. (2009) reported greater feed intake and BW from 7 to 21 d of

79

age when poults were fed medium particle size corn at 606 µm as compared to coarse (806

µm) or fine (380 µm) corn.

The percentage of feed fines did not affect feed intake. Cutlip et al. (2008) reported

increased feed intake and BW gain when broilers were fed pelleted diets as compared to

mash diets. Parsons et al. (2006) reported increased BW and improved FCR when hard

pellets (90.4% PDI) were fed as compared to soft pellets (86.2% PDI). Reduction in feed

intake in the presence of high levels of fines has been typically related to feed flow problems

at the feeder. Feeders were shaken three times daily after 14 d of age in order to keep feed

available at all times, regardless of the amount of fines in the feed. However, the percentage

of feed fines had a negative effect on BW at 35 and 42 d of age. Birds fed diets with 0% fines

had a greater BW than birds fed diets with 50% fines. Dozier et al. (2010) reported increased

growth rate and feed consumption during the grower and finisher phases when broilers

received pelleted diets as compared to broilers fed mash diets. Previous studies had reported

improved FCR with pelleted diets as compared to mash or diets with poorer pellet quality

(Jensen, 2000; Nir and Ptichi, 2001). According to Jensen (2000), as the pellet quality was

improved there was decreased feed wastage and energy expenditure during eating.

3.4.3. Organ Development

Birds that consumed diets with 30% DDGS exhibited greater relative proventriculus

weight (P≤0.05) than birds fed diets with 15% DDGS. The proventriculus or “gastric

stomach” has been reported to be responsible for gastric acid secretion required for protein

denaturation and activation of pepsinogen to pepsin (Rynsburger, 2009). Since the diets with

80

30% DDGS possessed greater crude protein, pepsinogen and hydrochloric acid secretion

were likely stimulated, which resulted in greater proventriculus weight. Birds fed diets with

coarse DDGS (745 µm) had greater relative gizzard weight (P≤0.05) than birds that

consumed diets with fine DDGS (482 µm) at 42 d of age. Jacobs et al. (2010) reported a

linear increase in gizzard weight in three different experiments as the particle size of corn

was increased from 557 to 1,387 µm. Nir et al. (1994) reported an increase of 26 and 41% in

gizzard weight when birds were fed medium (1,132 µm) and coarse (2,028 µm) mash as

compared to birds fed fine mash (627 µm). In addition, as the percentage of fines in the feed

increased, there was an increase in the relative weight of the gizzard. According to Behnke

(1994), pelleting increased bulk density of the mash. Diets with 25 and 50% fines likely

required a greater volume to accommodate the same amount of feed in the gizzard.

3.4.4. Nitrogen and Energy Digestibility

The results of this experiment showed that the percentage of fines in the feed did not

have any influence on nitrogen and energy digestibility. The results also demonstrated that

the inclusion level of DDGS in the feed had no significant effects on excreta nitrogen, crude

protein content, gross energy, or overall gross energy digestibility. Min et al. (2011) reported

an increased excreta nitrogen and crude protein from diets that contained 30% DDGS when

compared to a control diet without DDGS. In addition, the particle size of the DDGS had no

significant effects on excreta nitrogen, crude protein, and gross energy. As shown in Table 6,

the results demonstrated that inclusion of 30% DDGS in the diet significantly decreased

apparent metabolizable energy (AME) and nitrogen corrected apparent metabolizable energy

81

(AMEn) (P≤0.05) of the diet.

There was a numerical trend with reference to particle size of DDGS on nitrogen

retention (P=0.057). The birds fed 482-µm-DDGS exhibited numerically greater nitrogen

retention than birds fed 745-µm-DDGS. In addition, birds fed 482-µm-DDGS had improved

AME, AMEn, and overall gross energy digestibility as compared to birds fed 745-µm-

DDGS. Small particles have been associated with an enlarged surface area and greater

interaction with digestive enzymes, which may have increased nutrient digestibility

(Goodband et al., 2002). In addition, Parsons et al. (2006) reported decreased nitrogen and

lysine retention in broilers when the particle size of corn decreased from 2,242 to 781 µm.

The percentage of fines in the final feed did not have an influence on nitrogen retention and

digestibility or AMEn.

The results of this study indicated that up to 30% dietary DDGS could be feed in

broiler diets from 1-42 d of age if diets are formulated on a digestible amino acid basis.

Further grinding of DDGS had a negative affect on pellet quality likely due to fat liberation

of the protein matrix and poor pellet agglomeration. In addition, increasing the dietary

inclusion of DDGS had a slightly negative effect on pellet quality, but in general the pellet

quality of all diets was excellent (>80% PDI), which suggested that fat addition prior

pelleting must be monitored closely if high dietary inclusion of DDGS are used. In general,

birds performed better when fed fine-grind DDGS with no more than 25% fines in the feed as

compared to birds that consumed coarse-grind DDGS diets with 50% fines.

82


Table 1. Determined and calculated chemical composition of the distillers dried grain with

solubles (DDGS) (% as-fed basis, unless stated otherwise) as received from the supplier

Item

Determined chemical composition1

Dry matter 85.35

Crude protein 26.81

Ether extract 9.83

Crude fiber 8.40

Ash 4.73

Calcium 0.10

Total phosphorus 0.80

Calculated chemical composition

AMEn, kcal/g 2.71

Digestible amino acids

Lysine 0.57

Methionine 0.47

TSAA 0.84

Threonine 0.76

Tryptophan 0.17

Arginine 1.00 1In duplicate

83


Item Starter Grower 15% DDGS Grower 30% DDGS

Ingredient ——————————— (%) ——————————

Corn 50.05 49.48 38.18

Soybean meal, 48% CP 36.25 27.00 22.56

DDGS 6.00 15.00 30.00

Dicalcium phosphate, 18.5% P 1.98 1.55 1.184

Poultry fat 3.00 4.42 5.39

Limestone 1.36 1.21 1.39

Salt 0.38 0.41 0.36

L-Threonine, 99% 0.06 0.05 0.03

DL-Methionine, 99% 0.37 0.29 0.24

L-Lysine-HCl, 78% 0.19 0.24 0.30

Vitamin premix1 0.05 0.05 0.05

Mineral premix2 0.10 0.10 0.10

Choline chloride, 60% 0.10 0.10 0.10

Selenium premix3 0.05 0.05 0.05

Coccidiostat4 0.05 0.05 0.05

Titanium Dioxide 0.00 0.50 0.50


Metabolizable energy, kcal/g 3.04 3.15 3.15

Crude protein 23.20 21.10 22.20

Crude fat 5.41 7.62 9.66

Calcium 1.05 0.90 0.90

Available phosphorus 0.50 0.45 0.45

Digestible lysine 1.27 1.10 1.10

Digestible TSAA 0.94 0.84 0.84

Digestible threonine 0.84 0.73 0.73

Digestible arginine 1.39 1.18 1.15 1 Vitamin premix provided the following per kg of diet: vitamin A, 6600 IU; cholecalciferol, 1.980 IU; niacin, 55 mg; α-

tocopherol, 33 mg; pantothenic acid 11 mg; riboflavin, 6.6 mg; pyridoxine, 4 mg; menadione, 2 mg; folic acid, 1.1 mg;

thiamin, 2 mg; vitamin B12, 0.02 mg; and biotin, 0.13 mg. 2 Mineral premix provided the following per kg of diet: Zn, 120 mg; Mn, 120 mg; Fe, 80 mg; Cu, 10 mg; I, 2.5 mg; Co, 1.0

mg. 3 Selenium premix provided 0.2 mg/kg Se. 4 Monensin was included at 99 mg/kg (Coban 90, Elanco Animal Health, Indianapolis IN, USA).

84

Table 3. Effect of particle size and DDGS inclusion on pellet durability index (PDI) and feed

pellet production rate

DDGS

Inclusion1 DDGS Particle

Size1 PDI

Pellet Production

Rate

(%) (µm) (%) (kg/hr)

Main Effects

15 85.68A 845a

30 82.28B 814b

SEM2 0.31 7

745 85.77A 808B

482 82.20B 851A

SEM2 0.31 7

Interaction Effects

15 745 88.30A 836A

15 482 83.07B 854A

30 745 83.24B 780B

30 482 81.33C 848A

SEM3 0.40 8

Source of variation ——————————— P-value ———————————

DDGS inclusion 0.001 0.015

DDGS particle size 0.001 0.002

DDGS inclusion x DDGS particle size 0.002 0.009 a-b Means with different superscripts in the same column differ significantly (P ≤ 0.05). A-C Means with different superscripts in the same column differ significantly (P ≤ 0.01). 1 Treatments consisted of two inclusions (15 and 30%) and two particle sizes (745 and 482 µm) of DDGS. 2 Standard error of the means for DDGS inclusion and DDGS particle size effect (n = 12). 3 Standard error of the means for the interaction of DDGS inclusion and DDGS particle size effect (n = 6).

85

Table 4. Effect of particle size, DDGS inclusion, and percentage of fines on feed on BW, feed intake, and feed conversion ratio

(FCR) of broilers from 1 to 42 d of age.

a-b Means with different superscripts in the same column differ significantly (P ≤ 0.05). A-B Means with different superscripts in the same column differ significantly (P ≤ 0.01). 1 Treatments consisted of two inclusions of DDGS (15 and 30%), two particle sizes of DDGS (coarse-745 µm and fine-482 µm), and 3 percentages of feed

fines (0, 25, and 50%). 2 FCR = Feed intake per pen/total pen BW gain, including weights of mortality that occurred during each time period. 3 Standard error of the means for DDGS inclusion and DDGS particle size effect (n = 36). 4 Standard error of the means for percentage of fines in the feed (n = 24).

DDGS

Inclusion1 DDGS Particle

Size1 Fines in

Feed1

BW

Feed Intake

FCR2

14 d 35 d 42 d 1-14 d 1-35 d 1-42 d 1-14 d 1-35 d 1-42 d

(%) (µm) (%) ————— (g) ————— ————— (g) ————— ——— (g:g) ———

Main Effects

15 368 2066 2860 461 3121 4533b 1.28 1.54 1.60b

30 370 2067 2850 459 3145 4601a 1.27 1.54 1.63a

SEM3 2 11 16 4 19 25 0.01 0.01 0.01

745 367 2060 2832b 457 3111 4534b 1.27 1.54 1.62

482 370 2073 2877a 463 3156 4600a 1.27 1.54 1.62

SEM3 2 11 16 4 19 25 0.01 0.01 0.01

0 368 2097a 2897A 461 3175 4597 1.28 1.53 1.60

25 368 2060ab 2855AB 458 3102 4560 1.28 1.54 1.62

50 370 2042b 2810B 461 3152 4544 1.27 1.55 1.62

SEM4 3 14 19 4 24 30 0.01 0.01 0.01

Source of variation ————————————————— P-value —————————————————

DDGS inclusion 0.590 0.904 0.635 0.742 0.370 0.050 0.455 0.797 0.023

DDGS particle size 0.422 0.420 0.047 0.308 0.108 0.050 0.653 0.623 0.838

Fines in feed 0.784 0.022 0.009 0.930 0.282 0.481 0.555 0.459 0.780

86

Table 5. Effect of particle size, DDGS inclusion, and percentage of feed fines on relative

gizzard and proventriculus weight at 42 d of age

DDGS

Inclusion1

DDGS Particle

Size1

Fines in

Feed

Relative Weight

Gizzard Proventriculus

(%) (µm) (%) (g/100g BW)

Main Effects

15 9.75 2.47b

30 9.64 2.64a

SEM2 0.16 0.05

745 9.96a 2.57

482 9.44b 2.54

SEM2 0.16 0.05

0 9.09B 2.64

25 9.85A 2.51

50 10.15A 2.52

SEM3 0.20 0.06

Source of variation ———— P-value ————

DDGS inclusion 0.553 0.012

DDGS particle size 0.031 0.632

Fines in feed 0.007 0.195 a-b Means with different superscripts in the same column differ significantly (P ≤ 0.05). A-B Means with different superscripts in the same column differ significantly (P ≤ 0.01). 1 Treatments consisted of two inclusion levels of DDGS (15 and 30%), two particle sizes of DDGS (coarse-745

µm and fine-482 µm), and 3 percentages of feed fines (0, 25, and 50%). 2 Standard error of the means for DDGS inclusion and DDGS particle size effect (n = 144). 3 Standard error of the means for percentage of feed fines (n = 96).

87

Table 6. Effect of particle size, DDGS inclusion, and percentage of feed fines on nitrogen (N), crude protein (CP), and energy

utilization (AME, AMEn, and GE) of male broilers from 1 to 42 d of age

DDGS

Inclusion

DDGS Particle

Size1

Fines in

Feed

N

Excreta

CP

Excreta

N

Retention

GE

Excreta

AME

AMEn

GE

Digestibility

(%) (µm) (%) (%) (%) (%) (kcal/kg) (kcal/kg) (kcal/kg) (%)

Main Effects

15 2.82 17.64 70.65 3810 2832b 2809b 74.45

30 2.88 17.96 69.79 3788 2868a 2845a 75.79

SEM2 0.04 0.23 0.39 18 12 12 0.58

745 2.85 17.81 69.68 3816 2816B 2793B 73.86B

482 2.85 17.80 70.76 3782 2884A 2861A 76.39A

SEM2 0.04 0.23 0.39 18 12 12 0.58

0 2.87 17.93 70.49 3837 2859 2836 74.58

25 2.85 17.81 69.99 3786 2842 2819 75.20

50 2.83 17.67 70.18 3774 2850 2827 75.58

SEM3 0.05 0.30 0.49 23 15 15 0.74

Source of variation ———————————————— P-value ——————————————

DDGS inclusion 0.341 0.335 0.128 0.416 0.037 0.035 0.111

DDGS particle size 0.991 0.977 0.057 0.181 0.001 0.001 0.004

Fines in feed 0.629 0.820 0.757 0.102 0.695 0.701 0.607 a-b Means with different superscripts in the same column differ significantly (P ≤ 0.05). A-B Means with different superscripts in the same column differ significantly (P ≤ 0.01). 1 Treatments consisted of two inclusions of DDGS (15 and 30%), two particle sizes of DDGS (coarse-745 µm and fine-482 µm), and 3 percentages of feed

fines (0, 25, and 50%). 2 Standard error of the means for DDGS inclusion and DDGS particle size effect (n = 144). 3 Standard error of the means for percentage of feed fines (n = 96).

88

Figure 1. Average particle size and particle size distribution of DDGS used in broiler diets

during the grower period as received (coarse-745 µm) and after grinding (fine-482 µm) in a

hammer mill equipped with 1.6 mm screen.

89

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95

CHAPTER IV

EFFECT OF INCLUSION LEVEL AND METHOD OF ANALYSIS FOR CRUDE

FAT OF DDGS ON NUTRIENT DIGESTIBILITY, FOOTPAD LESIONS, AND

BROILER LIVE PERFORMANCE

96

4.1. ABSTRACT

Research has shown that up to 30% of DDGS could be used when broiler diets were

formulated on a digestible amino acid basis, but the maximum inclusion level of DDGS

when diets were formulated on a crude protein basis remained unclear. The ME value of

DDGS has typically been calculated based on crude fat, crude protein, and fiber content.

Crude fat of DDGS has been determined by ether extract (AOAC 920.39) or by including an

acid hydrolysis pretreatment (AOAC 954.02), which has generally yields about 2% higher

crude fat values and thus about 2.2% higher ME values. The objective of this study was to

evaluate the effect of DDGS inclusion level and the method of CF analysis on pellet quality,

nutrient digestibility, incidence of footpad lesions, and broiler live performance. A total of

1,050 male broiler chicks were randomly distributed among 5 treatments with 6 replicate

pens per treatment and 35 birds per pen. The treatments consisted of a control diet without

DDGS and a factorial arrangement of two analytical methods for CF analysis (AOAC 920.39

and AOAC 954.02) and two DDGS inclusion levels (15 and 30%). The DDGS ME values

used for feed formulation were 2,631 and 2,689 kcal/kg based upon these two analytical

methods. Feed consumption and BW were determined at 14, 35, and 49 d of age, and FCR

calculated. At 35 and 49 d ileal samples were obtained for nutrient digestibility analyses.

Footpad lesion scores were evaluated at 50 d of age. The analytical method AOAC 954.02

resulted in lower mixer fat addition and improved pellet quality (P≤0.01). In contrast,

increasing DDGS inclusion level to 30% reduced pellet quality (P≤0.01), BW (P≤0.01), feed

efficiency (P≤0.01), protein digestibility (P≤0.01), and increased footpad lesion score

(P≤0.01). It was concluded that broilers could be fed up to 15% DDGS when diets were

97

formulated on a crude protein basis, while the method of estimating crude fat and ME had a

marginal effect on live performance.

Key words: digestibility, energy, footpad, pellets

4.2. INTRODUCTION

The rapid increase in production of corn-based ethanol has resulted in increased

amounts of distillers dried grains with solubles (DDGS) entering poultry feed formulations as

a source of protein, phosphorus, and energy to replace corn and soybean meal (SBM). In

poultry diets, DDGS had been reported to possess lower amino acid bioavailability,

especially lysine and tryptophan (Baker, 2009). DDGS has been reported to contain a high

level of non-starch polysaccharides (NSP), which limits its inclusion in poultry diets (Choct,

2006). Lumpkins et al. (2004) reported that broilers could be fed 6% DDGS in the starter

phase and up to 12 and 15% during the grower and finisher phases without affecting live

performance.

Energy and essential amino acids have been identified as the most costly and essential

nutrients for live performance (Leeson, 2009). It has become essential to precisely measure

the available energy content of an ingredient in order to make precise feed formulations.

According to Batal and Bregendahl (2011), the most common method to determine the

energy value of an ingredient was the nitrogen corrected metabolizable energy (MEn). The

MEn of DDGS has been calculated based on its chemical composition, which has included

crude fat, crude protein, crude fiber, and possibly ash content. According to Batal and Dale

(2006), crude fat content is the best single indicator for MEn (r2 = 0.29), but the addition of

98

other chemical components, such as crude protein, fiber, and ash, improves the accuracy of

the prediction equation (r2

= 0.45). However, the best method to analyze crude fat content of

DDGS remains unclear. The most common methods of crude fat determination in feed

ingredients are AOAC methods 920.39 and 954.02 (AOAC, 2006). Method 954.02, which

involves an initial acid hydrolysis step, results in approximately 2% higher crude fat content

than method 920.39, which uses ether extract only. Previous research conducted in our

laboratory (unpublished data) found that when diets were formulated on a digestible amino

acid level, birds could be fed up to 30% DDGS without affecting live performance. However,

there is the necessity to investigate maximum inclusion of DDGS when the diets were

formulated on a crude protein or total amino acid basis. High dietary inclusion of DDGS has

been reported to reduce nitrogen retention and increased nitrogen excretion into the litter of

poultry (Roberts at al., 2007; Applegate et al., 2009). Shepherd and Fairchild (2010) reported

that litter quality and nutrition were the major factors that influenced footpad dermatitis

(FPD) in poultry. Increased ammonia in the litter, particularly in wet litter conditions, has

also been associated with increased incidence of footpad lesions in poultry. The objective of

this study was to evaluate the effect of dietary inclusion levels and metabolizable energy

value estimation method of DDGS on nutrient digestibility, footpad lesion score, and broiler

live performance.

99


4.3.1. DDGS analyses

A lot of DDGS was obtained from a local elevator in Selma, NC and a sample of it

was analyzed for ether extract (method 920.39), ether extract after HCl acid hydrolysis

(method 954.02), crude protein (N x 6.25) (method 990.03), and crude fiber (method 962.09;

AOAC, 2006) prior to feed formulation. Dry sieving according to ASAE method S319.3

(ASABE, 2007) was used to determine the particle size of DDGS with the addition of sieve

agitators and 0.5 g of dispersing agent per 100 g of sample.

4.3.2. Diets

Diets composed mainly of corn, SBM, and DDGS were formulated to meet or exceed

suggested minimum requirements of Ross 708 broilers (Aviagen, 2007) (Table 1). Diets were

formulated on a crude protein basis and were calculated to be isocaloric and isonitrogenous.

The grower and finisher diets contained 0.5% titanium dioxide, which was used as an

indigestible marker for nutrient digestibility determination. Feed was produced at the North

Carolina State University Feed Mill Educational Unit (Raleigh, NC) following current Good

Manufacturing Practices (GMP). Dry ingredients were mixed using a counterpoise mixer

(Model: TRDB126060, Hayes & Stolz, Fort Worth, TX). The mixed diets were conditioned

to 88°C for 45 seconds, and then pelleted using a pellet mill (Model PM1112-2, California

Pellet Mill Co., Crawfordsville, IN) equipped with a 3.5 mm x 36 mm die. Pellets were

cooled with ambient air in a counter-flow cooler (Model VK09x09KL, Geelen Counterflow

USA Inc., Orlando, Florida).

100

4.3.3. Bird Husbandry

The care of the animals used in this trial conformed to the Guide for Care and Use of

Animals in Agricultural Research and Teaching (FASS, 2010). A total of 1,050 male Ross

708 broilers (Aviagen Inc., Huntsville, AL) were obtained from the university broiler breeder

flock. Birds were hatched at the research location and then reared in a curtain-sided, heated,

and fan ventilated broiler house until 49 d of age. Birds were randomly allocated with 35

birds per pen to 30 pens in total. Each pen (120 x 380 cm) contained one bell-type drinker

and two tube feeders and was assigned to 1 of 5 dietary treatment combinations with 6

replicate pens per combination. Birds were raised on used litter that was top-dressed with

new wood shavings at the start of the study and had ad libitum access to water and feed

throughout the study. Three supplemental feeder flats were used until 7 d of age, 2 feeder

flats until 10 d, and 1 feeder flat until 14 d of age. Small amounts of feed were added twice

daily to the feeder flats to guarantee appropriate feed consumption. Feed that remained in the

feeder flat at 14 d was screened and added to the tube feeders before weigh back. A common

starter diet that contained 6% DDGS was used until 14 d of age in order to adapt the

gastrointestinal tract (GIT) of the birds to efficiently digest DDGS and to avoid sudden

changes in the nutrition and feeding program. Birds were fed 0.9 kg/bird of starter, 2.7

kg/bird of grower, and 4.1 kg/bird of finisher feed. Starter diets were fed as crumbles, and

grower and finisher diets were fed as pellets. Starter and grower feed were adjusted to

provide the same quantity of each feed per bird in order to maintain a similar cumulative

nutrient package.

101

Feed additions were weighed, recorded, and added in 454 g (1 lbs.) increments per

bird alive. Feeders were shaken once per day from 1 to 14 d, and three times per day from 15

to 49 d to maintain fresh feed in front of the birds, as well as to stimulate and prevent

variation in feed intake due to feed flow characteristics. Photoperiods were 23L:1D from 1 to

7 d, 22L:2D to 14 d, and 20L:4D to 21 d with natural light employed from 22 to 42 d of age.

High and low temperatures were recorded daily and stirring fans were used to maintain a

uniform temperature in the entire house. The target temperatures were 32°C from placement

to 7 d, 29ºC to 14 d, 27ºC to 21 d, and ambient thereafter.


Standard processing data, such as pellet production rate and conditioning temperature,

were controlled closely during feed manufacturing. The durability of the pellets was

determined according to the American Society of Agricultural Engineers standard method

S269.4 (ASABE, 2007). Prior to testing, approximately 2,500 g of pellets were collected

from each treatment with 6 samples taken at evenly spaced time intervals upon discharge

from the pellet mill and placed into cooling trays at a depth of approximately 1 cm and

cooled for 8 minutes with ambient air using a counter flow pellet cooler. The standard tumble

box method was used a device locally constructed and operated in accordance with the

ASABE standard. Two sub-samples of pellets were screened using a US #6 sieve (3.35 mm)

to remove the fines produced during the pelleting process and 500 g of each placed into 1 of

the 4 compartments of the tumbling box. For the modified method three hex nuts (50 g/nut)

were added in the tumble box compartment. The sub-samples were tumbled at 50 rpm for 10

102

min. After tumbling each sub-sample was sifted again using a US #6 sieve to remove the

fines and the re-weighed. The pellet durability index was calculated as the ratio of the weight

of the pellets that remained in the sieve after tumbling relative to the initial weight before

tumbling (500 g) and reported as a percentage. The compartments in the tumbling box were

cleaned by hand after each pellet durability test in order to remove any fines build-up in the

corners.

Feed and average BW on a pen basis were recorded at the beginning of the

experiment and at the end of the starter, grower, and finisher periods for determination of

BW gain, feed consumption, and feed conversion ratio (FCR). Mortality was monitored and

recorded twice daily and the BW of birds that died was used to adjust the FCR. Cumulative

FCR was calculated for the periods of 1-14, 1-35, and 1-49 d of age.

At 35 and 49 d of age, three birds in each pen were killed by cervical dislocation and

ileal digesta was collected (2 cm posterior of Meckel’s diverticulum to 2 cm anterior of the

ileal-cecal junction) by gently squeezing the ileal contents in a manner that provided

sufficient sample for digestibility analysis. Ileal digesta was placed on ice, and subsequently

frozen at -20ºC. Ileal samples were lyophilized and subsequently ground through a 0.5 mm

screen. At 50 d of age, footpad lesion scores on each bird in each pen were evaluated using a

10-point visual scale from 0 to 9 following the methodology of Allain et al. (2009).

103

4.3.5. Ileal analyses

Titanium dioxide analysis was used to calculate ileal digestibility of energy, fat, and

protein (Fan et al., 1994; Marty et al., 1994). Fat analysis of feed and ileal samples were

performed using the crude fat extraction method (AOAC 920.39) and the total fat extraction

method (AOAC 954.02), which included a previous acid hydrolysis with 5N HCl (AOAC,

2006). Crude fat analyses were performed using the Ankom XT15

extractor and the AnkomHCl

hydrolysis system (Ankom Technology, Macedon, NY). Nitrogen content of the feed and

ileal samples (AOAC 990.03) was determined using a LECO model FP 2000 N combustion

analyzer (LECO Corp., St. Joseph, MI) (AOAC, 2006). Dry matter content of the ground

diets and the freeze-dried ileal samples was determined using method 930.15 by drying the

samples at 135ºC for 2 h (AOAC, 2005).


The experiment was analyzed as ANOVA using a randomized complete block design

to identify main effects and interactions. The treatments consisted of a factorial arrangement

of 3 inclusion levels of DDGS (0, 15, and 30% DDGS) and two analytical methods to

analyze the crude fat content of DDGS (method 920.39 and method 954.02, AOAC, 2006). A

pen of broilers served as the experimental unit for the statistical analysis of the live

performance data. Data were analyzed using PROC GLM (SAS, 2006). Statements of

statistical differences were based upon P≤0.05 unless otherwise indicated. Differences

between means were separated with the least significant difference test.

104



There was a significant effect of the dietary inclusion level of DDGS on pellet

durability (P≤0.01) of the grower and finisher diets. Pellet durability was negatively affected

when the inclusion level of DDGS was increased (Table 2). As the inclusion level of DDGS

increased from 0% to 30%, pellet durability decreased from 85% to 75% in the grower diets

and from 79% to 61% in the finisher diets. The main factor that likely contributed to the

reduced pellet quality was a higher amount of poultry fat added in the mixer to compensate

for the lower ME level as the dietary inclusion level of DDGS increased (Fig. 1 and 2).

DDGS replaced corn and SBM in the experimental diets and since DDGS had lower ME

content than corn, more fat was added to the diet in the mixer as the inclusion level of DDGS

increased. Fat functions as a lubricant as the conditioned mash passes through the die (Stark,

1994; Thomas et al., 1998), thus decreasing friction and feed pellet compression. Richardson

and Day (1976) reported that increasing the percentage of added fat into the mixer from 1 to

4% increased the percentage of feed fines in the pelleted feed from 18 to 31.6% and it also

increased production rate from 11.6 to 13.2 ton/hr. Fahrenholz (2008) reported a decrease in

pellet quality when the inclusion level of DDGS increased from 0 to 20%. However, the

pellet quality of diets containing 10% DDGS did not differ from the control diets without

DDGS.

The analytical method of crude fat analysis had an effect on pellet quality (P≤0.01)

and feed production rate (P≤0.05). Diets in which the level of fat in the DDGS was analyzed

105

using method 154.02 had a higher PDI (P≤0.01) but lower production rate as compared to

diets in which DDGS were analyzed using method 990.03. This was logical since method

154.02 presumed a greater fat level in the DDGS. Hence, less fat was added in the mixer in

order to obtain the desired dietary ME level. Stark (1994) reported that increasing the amount

of added fat in the mixer by 1.5 and 3% decreased pellet quality by 2% and 5%, respectively.

Salmon (1985) reported a decrease in pellet durability with increased inclusion of added fat

in the mixer. In contrast, Wang et al. (2008a) reported less variation in percentage fines

generated in DDGS containing diets when the amount of fat added in the mixer was

maintained constant.

An interaction was observed between DDGS inclusion level and the analytical

method (P≤0.05) on pellet quality in the grower and finisher diets. When the DDGS was

analyzed using method 154.02, there were no differences in pellet durability between diets

that contained either 15 or 30% DDGS. However, when DDGS was analyzed using method

990.03 the pellet durability decreased as the dietary inclusion of DDGS increased from 15 to

30%. In addition, an interaction between dietary DDGS inclusion and analytical method

(P≤0.01) on feed production rate was observed in the grower feed. The feed production rate

was not different at either 15 or 30% dietary inclusion of DDGS when the DDGS sample was

analyzed using method 990.03. However, when the DDGS sample was analyzed using

method 154.02, the feed production rate increased (P≤0.01) as the inclusion of DDGS was

increased from 15 to 30%. Altered levels of added fat in the mixer explained these results.

When diets were formulated using method 154.02, the difference in mixer fat addition

106

between 15 and 30% DDGS diets was approximately 0.45%, but when diets were formulated

using method 990.03 the difference was approximately 0.64% (Table 1).

4.4.2. Broiler Live Performance

No differences were observed for BW, FCR, and feed consumption at 14 d of age.

This was expected since all birds received a common starter diet that contained 6% DDGS.

Loar et al. (2010) reported an interaction between the starter and grower diets regarding the

inclusion of DDGS as birds that consumed diets with 8% DDGS in the starter maintained a

normal feed consumption when the dietary inclusion of DDGS was increased to 22.5 or 30%

in the grower feed. However, birds that consumed diets without DDGS in the starter diet

exhibited decreased feed consumption when DDGS were increased to 22.5 and 30% in the

grower diet.

There was a main effect of dietary inclusion level of DDGS on BW and FCR at 35

and 49 d of age (Table 3). Birds fed the control diet without DDGS or 15% DDGS had a

greater BW than birds fed the diets containing 30% DDGS (P≤0.01) at 35 d of age. These

results were in agreement with Wang et al. (2008b), who showed that there was as significant

decrease in BW gain in the grower period when dietary inclusion of DDGS exceeded 20%.

Loar et al. (2010) reported similar results with no differences in BW gain from 14 to 28 days

of age when DDGS comprised 15% of the diet. Wang et al. (2007) reported that feeding diets

containing 30% DDGS decreased live performance and breast meat yield, but diets

containing 15% DDGS had performance comparable to the control diet without DDGS. At

49 d of age, the birds fed diets without DDGS had a greater BW than birds fed diets

107

containing 15 or 30% DDGS (P≤0.01). The increased BW in diets without DDGS was not

related to increased feed consumption, thus improving FCR significantly (P≤0.01). At 35 and

49 d of age, birds fed diets without DDGS or 15% DDGS exhibited improved FCR than birds

fed diets that contained 30% DDGS (P≤0.01). Wang et al. (2008) reported reduced feed

efficiency as the dietary inclusion of DDGS increased from 20 to 30% in the grower phase.

During the ethanol processing, DDGS are exposed to a drying process, thus the risk of heat

damaged proteins. Fiene et al. (2006) measured lysine digestibility from eight different

sources and reported values that ranged from 56.9 to 72.2%. The poor feed efficiency

observed in diets that contained 30% DDGS may have been related to poor amino acid

digestibility. If the drying process of DDGS is not monitored closely, overheating could

initiate the Maillard reaction, which has been reported to be very detrimental to the

nutritional quality of DDGS by causing reducing carbohydrates and amino acids to react and

become chemically bound (Noll et al., 2001).

The analytical method used to measure the crude fat in DDGS did not have an effect

on broiler live performance throughout the study, which suggested that the crude fat could be

analyzed using either method. The ME values of DDGS were 2,689 kcal/kg for method

154.02 and 2,631 kcal/kg for method 990.03. However, analyzing the crude fat content of

DDGS using ether extract alone is a more conservative method to guarantee optimum broiler

performance. The American Feed Industry Association (AFIA, 2007) has recommended the

method AOAC 945.16 (Soxhlet extraction with petroleum ether) without acid hydrolysis to

analyze crude fat in the DDGS.

108

4.4.3. Nutrient Digestibility and Footpad Lesion Scores

The dietary inclusion level of DDGS and the analytical method used to measure the

crude fat in DDGS did not have an effect on crude fat digestibility. However, the dietary

DDGS inclusion level did have a significant effect on nitrogen digestibility. Birds fed diets

without DDGS or 15% DDGS had greater nitrogen digestibility at 35 (P≤0.05) and 49

(P≤0.01) d of age than birds fed diets containing 30% DDGS. Min et al. (2011) reported that

diets containing 30% DDGS increased the levels of nitrogen and protein in the excreta and

decreased nitrogen retention as compared to diets without DDGS. The decreased nitrogen

digestibility in diets containing 30% DDGS could be related to reduced amino acids

digestibility, particularly lysine as it is most susceptible to Maillard reactions with reducing

sugars upon heat processing. Since poultry do not possess enzymes that break the lysine-

sugar complex bond, the lysine is rendered nutritionally unavailable (Batal and Bregendahl,

2011). Aldeola and Ilelegi (2009) reported that increasing the inclusion of DDGS from 0 to

300 and 600 g/kg in broiler diets from 14 to 21 d of age decreased nitrogen retention from

65.15% to 51.12 and 33.6 %, respectively. Although analytical method to measure the crude

fat content of DDGS did not affect footpad lesions score in this study, the inclusion level of

DDGS in the diet did significantly affect footpad lesions score (P≤0.01) at 50 d of age. Birds

fed diets containing 30% DDGS exhibited greater severity of footpad lesions than birds fed

diets without or with 15% DDGS; this could be related to lower nitrogen digestibility (Fig.

3).

Pellet durability in this study was negatively affected when the inclusion level of

DDGS was increased from 0 to 30% principally due to a higher fat addition prior to pellet in

109

order compensate for a lower ME of DDGS compared to corn and to keep the diets

isocaloric. Generally speaking, the protein in DDGS is denatured by heat processing during

the drying process of DDGS and possible by alcohol during the fermentation process and

therefore is not longer functional as pellet binder during particle agglomeration. Additionally,

the higher amount free fat added in DDGS containing diets before pelleting interferes with

moisture and heat penetration into feed particles during mash conditioning and thus prevents

the hydrogen bonding during particle agglomeration during pellet compression in the die.

Since fat also increase the lubrication of the die and reduce frictional heat, less starch

gelatinization occurs in the surface of the pellet. The method 154.02 of fat analysis had a

positive effect on PDI, but lower production rate as this method presumed a higher

percentage of fat in the DDGS and thus less fat added prior to pelleting in order to keep diets

isocaloric. However, the method of fat analysis did not have a positive or negative effect on

nutrient digestibility, incidence of footpad lesions and broiler live performance. The

inclusion of 30% DDGS decreased nitrogen retention and increased the incidence of footpad

lesions. The results of this study indicated that up to 15% DDGS could be fed when diets

were formulated on a total amino acid basis.

110



Item Starter

Grower Finisher

0 DDGS

15 DDGS 30 DDGS

0 DDGS

15 DDGS 30 DDGS

AOAC

154.02

AOAC

990.03

AOAC

154.02

AOAC

990.03

AOAC

154.02

AOAC

990.03

AOAC

154.02

AOAC

990.03

Ingredient Name ——————————————————— (%) ————————————————————————

Corn 52.73 62.97 54.66 54.44 46.38 45.92 66.92 58.62 58.41 50.32 49.88

Soybean meal, 48% CP 33.25 30.92 23.74 23.78 16.56 16.63 26.17 19.00 19.03 11.82 11.89

DDGS 6.00 0.00 15.00 15.00 30.00 30.00 0.00 15.00 15.00 30.00 30.00

Poultry fat 3.62 1.11 1.56 1.74 2.00 2.38 1.83 2.28 2.46 2.73 3.10

Dicalcium phosphate 1.95 1.73 1.57 1.57 1.41 1.41 1.77 1.61 1.61 1.45 1.45

Vermiculite 0.00 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50

Titanium dioxide 0.00 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50

Limestone 0.96 0.85 0.96 0.96 1.06 1.08 0.86 0.98 0.98 1.09 1.09

Salt 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50

DL-Methionine, 99% 0.22 0.21 0.14 0.14 0.08 0.08 0.17 0.11 0.11 0.05 0.05

Vitamin premix1 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05

Mineral premix2 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20

Choline chloride, 60% 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20

L-Lysine-HCl, 78% 0.13 0.10 0.24 0.24 0.37 0.37 0.13 0.26 0.26 0.40 0.40

L-Threonine 0.10 0.07 0.07 0.07 0.07 0.08 0.09 0.09 0.09 0.09 0.09

Selenium premix3 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05

Coccidiostat4 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05


ME, kcal/g 2.95 2.87 2.87 2.87 2.87 2.87 2.95 2.95 2.95 2.95 2.95

Crude protein 22.00 20.00 20.00 20.00 20.00 20.00 18.00 18.00 18.00 18.00 18.00

Calcium 0.90 0.80 0.80 0.80 0.80 0.80 0.80 0.80 0.80 0.80 0.80

Available P 0.45 0.40 0.40 0.40 0.40 0.40 0.40 0.40 0.40 0.40 0.40

Lysine 1.26 1.14 1.14 1.14 1.14 1.14 1.03 1.03 1.03 1.03 1.03

TSAA 0.92 0.83 0.83 0.83 0.83 0.83 0.75 0.75 0.75 0.75 0.75

Threonine 0.83 0.74 0.74 0.74 0.74 0.74 0.69 0.69 0.69 0.69 0.69 1 Vitamin premix provided the following per kg of diet: vitamin A, 6600 IU; cholecalciferol, 1.980 IU; niacin, 55 mg; α-tocopherol, 33 mg; pantothenic acid 11 mg;

riboflavin, 6.6 mg; pyridoxine, 4 mg; menadione, 2 mg; folic acid, 1.1 mg; thiamin, 2 mg; vitamin B12, 0.02 mg; and biotin, 0.13 mg. 2 Mineral premix provided the following per kg of diet: Zn, 120 mg; Mn, 120 mg; Fe, 80 mg; Cu, 10 mg; I, 2.5 mg; Co, 1.0 mg. 3 Selenium premix provided 0.2 mg/kg Se. 4 Monensin was included at 99 mg/kg (Coban 90, Elanco Animal Health, Indianapolis IN, USA).

111

Table 2. Effect of inclusion level of DDGS and metabolizable energy value of DDGS on

pellet durability index (PDI) and pellet production rate

DDGS Inclusion

Level1 AOAC Method1

PDI2

Pellet Production Rate

Grower

Finisher

Grower Finisher

(%) ———— (%) ———— —— (kg/hr) ——

Main effects

0 85.23A 78.67A 679B 905

15 79.48B 69.25B 740A 915

30 75.07C 61.00C 744A 915

SEM3 0.57 0.73 2 4

AOAC 990.03 74.65B 61.83B 755A 920a

AOAC 154.02 79.90A 68.42A 728B 909b

SEM3 0.57 0.73 2 4

Interaction effects

15 AOAC 990.03 77.77b 68.17A 759A 919

30 AOAC 990.03 71.53c 55.50B 752A 921

15 AOAC 154.02 81.20a 70.33A 721C 910

30 AOAC 154.02 78.60ab 66.50A 735B 908

SEM4 0.81 1.03 2 5

Source of variation ————————— P-value ————————

DDGS inclusion level 0.001 0.001 0.001 0.079

Analytical method 0.001 0.001 0.001 0.029

DDGS inclusion level x analytical method 0.036 0.004 0.002 0.699 a-c Means with different superscripts in the same column differ significantly (P≤0.05). A-C Means with different superscripts in the same column differ significantly (P≤0.01). 1 Treatments consisted of three inclusion levels of DDGS (0, 15, and 30%) with two energy values of DDGS

that were determined by ether extract (2,631 kcal/kg) or acid hydrolysis (2,689 kcal/kg). 2 Pellet durability was measured according to American Society of Agricultural Engineers standard method

S269.4. 3 Standard error of the mean for DDGS inclusion level and method of fat analysis (n = 12). 4 Standard error of the mean for the interaction of DDGS inclusion level and method of fat analysis (n= 6).

112

Table 3. Effect of inclusion level of DDGS and metabolizable energy value of DDGS on BW, feed intake, and feed conversion

ratio (FCR) of broilers from 1 to 49 d of age

DDGS Inclusion

Level1

AOAC Method1

BW

Feed Intake

FCR2

14 d 35 d 49 d 1-14 d 1-35 d 1-49 d 1-14 d 1-35 d 1-49 d

(%) ———— (g) ———— ———— (g) ———— ————— (g:g) —————

Main effects

0 507 2693A 4356

A 660 4192 7765 1.44 1.59

B 1.91

C

15 504 2668A 4290

B 656 4133 7696 1.44 1.58

B 1.93

B

30 510 2605B 4193

C 661 4142 7688 1.43 1.62

A 1.97

A

SEM3

3 8 15 5 19 37 0.01 0.01 0.01

AOAC 990.03 507 2644 4249 658 4139 7705 1.44 1.60 1.94

AOAC 154.02 506 2629 4234 659 4137 7679 1.44 1.61 1.95

SEM3

3 8 15 5 19 37 0.01 0.01 0.01

Interaction effects

15 AOAC 990.03 503 2671 4287 655 4132 7688 1.44 1.59 1.93

15 AOAC 154.02 504 2666 4293 657 4135 7703 1.44 1.58 1.92

30 AOAC 990.03 512 2617 4211 662 4145 7722 1.43 1.61 1.96

30 AOAC 154.02 508 2592 4175 660 4139 7654 1.44 1.63 1.97

SEM4

4 11 22 7 27 52 0.01 0.01 0.01

Source of variation —————————————————— P-value —————————————————

DDGS inclusion level 0.174 0.001 0.002 0.477 0.745 0.880 0.434 0.001 0.002

Analytical method 0.722 0.201 0.491 0.978 0.947 0.616 1.000 0.389 0.825

DDGS inclusion level x analytical method 0.528 0.386 0.347 0.809 0.880 0.434 0.530 0.139 0.510 a-c Means with different superscripts in the same column differ significantly (P ≤ 0.05). A-C Means with different superscripts in the same column differ significantly (P ≤ 0.01). 1 Treatments consisted of three inclusion levels of DDGS (0, 15, and 30%) with two energy values of DDGS that were determined by ether extract (2,631

kcal/kg) or acid hydrolysis (2,689 kcal/kg). 2 FCR = Feed intake per pen/total pen BW gain, including BW of mortality that occurred during each time period. 3 Standard error of the mean for DDGS inclusion level and method of fat analysis (n = 12). 4 Standard error of the mean for the interaction of DDGS inclusion level and method of fat analysis (n= 6).

113

Table 4. Effect of inclusion level of DDGS and metabolizable energy value of DDGS on protein, fat digestibility, and footpad

lesion score at 49 d of age

DDGS Inclusion

Level1 Analytical Method1

Digestibility at 35 d Digestibility at 49 d Footpad Lesion Score

Protein Fat Protein Fat (35 d) (49 d)

(%) ———— (%) ———— ————— (%) ———— ——— (Range 0-9) ———

Main effects

0 73.51a 87.63 69.66A 90.88 1.52b 3.51C

15 70.03b 87.86 69.84A 88.39 1.59b 3.77B

30 65.96c 87.35 62.03B 89.98 1.74a 4.32A

SEM3 1.33 1.43 1.87 1.72 0.05 0.09

AOAC 990.03 68.49 85.96 65.24 88.43 1.68 4.10

AOAC 154.02 67.50 89.25 66.63 89.94 1.73 4.01

SEM3 1.33 1.43 1.87 1.72 0.05 0.09

Interaction effects

15 AOAC 990.03 69.73 86.06 68.17 87.08 1.56 3.86

30 AOAC 990.03 67.25 85.86 62.31 89.78 1.65 4.33

15 AOAC 154.02 70.34 89.66 71.50 89.70 1.63 3.69

30 AOAC 154.02 64.67 88.83 61.76 90.18 1.84 4.32

SEM4 1.87 2.02 2.64 2.44 0.07 0.13

Source of variation —————————————————— P-value ——————————————————

DDGS inclusion level 0.043 0.802 0.007 0.521 0.025 0.001

Analytical method 0.606 0.119 0.603 0.544 0.452 0.513

DDGS inclusion level x analytical method 0.407 0.877 0.470 0.653 0.382 0.528 a-c Means with different superscripts in the same column differ significantly (P ≤ 0.05). A-C Means with different superscripts in the same column differ significantly (P ≤ 0.01). 1 Treatments consisted of three inclusion levels of DDGS (0, 15, and 30%) with two energy values of DDGS that were determined ether extract (2,631

kcal/kg) or acid hydrolysis (2,689 kcal/kg). 2 Footpads lesions were evaluated using a 10-point visual scale considering the severity of the lesion and the area of the footpad affected. 3 Standard error of the mean for DDGS inclusion level and method of fat analysis (n = 36). 4 Standard error of the mean for the interaction of DDGS inclusion level and method of fat analysis (n= 18).

114

Figure 1. Relationship between pellet durability index (PDI) and amount of fat added in the

mixer in grower diets containing 0, 15, and 30% DDGS analyzed by two methods of crude

fat analysis (Acid hydrolysis (AH)*-method 154.02 and ether extract (EE)**-method 990.03;

AOAC, 2006)).

115

Figure 2. Relationship between pellet durability index (PDI) and amount of fat added in the

mixer in finisher diets containing 0, 15, and 30% DDGS analyzed by two methods of crude

fat analysis (Acid hydrolysis (AH)*-method 154.02 and ether extract (EE)**-method 990.03;

AOAC, 2006)).

116

Figure 3. Relationship between nitrogen digestibility and incidence of footpad lesions (FPL)

as measured by the footpad lesion score in diets containing 0, 15, and 30% DDGS analyzed

by two methods of crude fat analysis (Acid hydrolysis (AH)*-method 154.02 and ether

extract (EE)**-method 990.03; AOAC, 2006)).

117

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Minnesota Nutrition Conference and Minnesota Corn Growers Association

Technical Symposium. Bloomington, MN.

Richardson, W., and E. J. Day. 1976. Effect of varying levels of added fat in broiler diets on

pellet quality. Feedstuffs (May 17):24

Roberts, S. A., H. Xin, B. J. Kerr, J. R. Russell, and K. Bregendahl. 2007. Effects of dietary

fiber and reduced crude protein in ammonia emission from laying-hen manure. Poult.

Sci. 86:1625-1632.

Salmon, R. E. 1985. Effects of pelleting, added sodium bentonite and fat in a wheat-based

diet on performance and carcass characteristics of small white turkeys. Anim. Feed

Sci. Technol. 12:223-232.


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89:2043-2053.

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70:59-78.


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Poult. Sci. 6:501-507.


2008a. Evaluation of corn distillers dried grains with solubles in broiler diets


density with constant 1% fat. Int. J. Poult. Sci. 7:630-637.

Wang, Z., S. Cerrate, C. Coto, F. Yan, and P. W. Waldroup. 2008b. Evaluation of high levels

of distillers dried grains with solubles (DDGS) in broiler diets. Int. J. Poult. Sci.

7:990-996.

121

CHAPTER V

EFFECT OF DDGS PARTICLE SIZE AND PELLET QUALITY ON GROWER-

FINISHER PIG PERFORMANCE

122

5.1. ABSTRACT

The objective of the study was to evaluate the effect of further grinding distillers dried grains

with solubles (DDGS) and the percentage feed fines on grower-finisher pig performance. A

total of 760 mixed sex pigs (28.8 ± 3.1 kg) were housed in a curtain-sided barn with

mechanical ventilation and totally slatted flooring. The experimental design consisted of a 2

x 2 factorial design with 2 particle sizes of DDGS (640 vs. 450 µm) and 2 levels of fines (0

and 25%). The four treatments were randomly distributed among 40 pens with 10 replicates

per treatment. Pigs were fed a common diet containing 30% DDGS and 6.5% supplemental

fat in 3 dietary phases grower (1 to 40 d), developer (41 to 83 d), and finisher (84 to 116 d).

Of the 6.5% supplemental fat in each diet, 1.5% was added in the mixer and 5.0% was added

post-pelleting. Diets were conditioned at 77°C for 45 seconds and then pelleted using a pellet

mill equipped with a 3.5 mm x 36 mm die. The fines produced during the pelleting process

were separated using a pellet screener and then mixed back with the whole pellets to obtain

the desired percentage fines in the final feed. Feeds were delivered and pen feed intake

recorded using an automatic feed delivery system (FeedPro). Feed consumption and BW

were determined at 1, 18, 40, 83, and 116 d on test and gain to feed (G:F) calculated. Data

was analyzed using PROC GLM in SAS. Pen was the experimental unit. Fixed effects

included DDGS particle size, percentage fines, and their interaction. The particle size of

DDGS did not impact (P > 0.05) overall ADG (836 vs. 842 g; P=0.65), ADFI (2205 vs. 2222

g; P=0.66), or G:F (2.64 vs. 2.64; P=0.95). Diets with 0% fines did not improve (P > 0.05)

ADG (843 vs. 835 g; P=0.48), ADFI (2224 vs. 2204 g; P=0.59), or G:F (2.64 vs. 2.64;

P=0.97) in comparison to diets with 25% fines. Results indicated that DDGS does not need

to be further ground at the feed mill and that up to 25% feed fines could be fed without

adverse effects on pig performance.

Key words: DDGS, particle size, fines, grinding

123

5.2. INTRODUCTION

Feed costs have represented a significant fraction of the production cost in swine

farming. Thus, producers have been constantly evaluating ways to improve live performance

and feed efficiency (Myers et al., 2013). Pelleting and particle size reduction are feed

processing methods to improve feed efficiency. The pelleting process has become an

important practice for the feed industry as an alternative to increase feed efficiency and

livestock performance (Zang et al., 2009). It allows for the inclusion of feedstuffs that have

poor flow characteristics (Stark, 2012), and reduces feed costs by facilitating the use of a

greater variety of low-cost feed ingredients without noticeable changes in the physical

properties of the feed (Behnke, 1996). Pelleting grower and finisher diets has been reported

to increase daily weight gain, feed intake, and improve feed efficiency of swine and poultry

(Wondra et al., 1995a; Jensen, 2000; Frikha et al., 2009; Abdollahi et al., 2011).

Increased inclusion of distiller’s dried grains with solubles (DDGS) in swine diets has

coincided with increased ethanol production, while reduced supply and increased prices of

corn and soybean meal (SBM), which has encouraged the use of higher quantities of DDGS

in swine diets. In fact, the swine industry has been the fastest growing sector in the U.S.A.

for DDGS use (Shurson and Noll, 2005). Dietary inclusion has been demonstrated to be as

high as 30% DDGS without affecting live performance and overall feed efficiency of

growing pigs (DeDecker et al., 2005; Cook et al., 2005). However, such high dietary

inclusion of DDGS has been reported to decrease pellet quality and feed mill throughput

(Behnke, 2007). DDGS contains less starch and more denatured protein than corn or SBM,

which contributes to reduce the pellet binding characteristics (Behnke and Beyer, 2002).

124

Reducing DDGS particle grind size may be an effective alternative to increase its inclusion in

swine diets without adverse effects on pellet quality and pellet mill operation efficiency.

Many feed ingredients, especially cereal grains, have been ground before their incorporation

into swine diets (Zang et al., 2009). Particle size reduction has been reported to improve

pellet quality and live performance in nursery and growing-finishing pigs (Healy et al., 1994;

Wondra et al., 1995a) by increasing the surface area of the digesta available for interaction

with digestive enzymes, and by allowing the digestive enzymes to release the nutrients more

effectively (Goodband et al., 2002; Fastinger and Mahan, 2003). In a preliminary study,

DeJong et al. (2011) reported a numerical improvement of 1.1% in F:G when DDGS were

further ground at the feed mill from 787 to 692 µm and incorporated into diets fed to

finishing pigs. However, this 95 µm difference in particle size of the DDGS was not

sufficient to affect overall pig growth performance. Therefore, the objective of the study

reported herein was to evaluate the effects of DDGS particle grind size and percentage pellet

fines on grower-finisher pig performance.


5.3.1. Diets

DDGS was obtained from a local elevator in Selma, NC and the calculated proximate

analyses are presented in Table 1. Experimental diet composition and analyzed nutrient

concentrations are presented in Table 2 for the 3 dietary phases used during the grower-

finisher period. Experimental diets within each phase of growth were formulated to meet or

125

exceed NRC suggested requirements (NRC, 1998) and contained the same nutrient

concentrations. The only factors that changed between the experimental diets were particle

size of the DDGS and the percentage fines in the final feed. Half of the DDGS (control diet)

were used as received from the supplier; the other half was further ground using a

hammermill (Model 1522, Roskamp Champion, Waterloo, IA) equipped with a 1.6 mm

screen to obtain fines particles. All diets were fed in pellet form during the entire grower to

finisher period.

Feed was produced at the North Carolina State University Feed Mill Educational Unit

(Raleigh, NC) following current Good Manufacturing Practices (GMPs). Dry ingredients

were blended in a counterpoise mixer (Model TRDB126060, Hayes & Stolz, Fort Worth,

TX) with 1.5% fat added in the mixer in order to follow normal industry practices and

produce high quality pellets. The remaining fat was added post-pelleting. Mash diets were

conditioned at 77°C for 45 seconds and then pelleted using a pellet mill (Model PM1112-2,

California Pellet Mill Co., Crawfordsville, IN) equipped with a 3.5 mm x 36 mm die. Pellets

were cooled using a counter flow pellet cooler (Model VK09x09KL, Geelen Counterflow

USA Inc., Orlando, Florida). The fines produced during the pelleting process were separated

using a pellet screener and then mixed back with the whole pellets to obtain the desired

percentage fines in the final feed.

5.3.2. Animal Husbandry

Pigs used in this experiment were Smithfield Premium Genetics (SPG) Landrace x

Large White dams mated to SPG Duroc pigs (Smithfield Premium Genetics, Roanoke

126

Rapids, NC). The experiment was conducted at a commercial research nursery to finishing

facility near Harrels, NC from July to November 2013. A total of 760 pigs with an initial BW

of 28.8 ± 3.1 kg were randomly allotted to 1 of 4 experimental treatments in a curtain sided

barn with mechanical ventilation. There were 19 pigs per pen and 10 pens per treatment.

Pens were located over a totally slatted floor with a deep pit for manure storage and each

contained 1 four-space self-feeder and 1 nipple drinker. Pigs were provided with ad libitum

access to feed and water for the duration of the study. Feed additions to each pen were

accomplished by a computerized feeding system (FeedPro; Feedlogic Corp., Willmar, MN)

capable of delivering and measuring feed additions for individual pens. Conventional dry

feeders were used with a minimum gap width of 1.78-cm to control feed flowability.

Treatments were arranged in a 2 x 2 factorial with the main effects of particle size of DDGS

(as received and further ground) and percentage fines in the final feed (0 and 25%).

Pigs were fed a common diet containing 30% DDGS in 3 dietary phases (29 to 40 kg

grower, 40 to 60 developer, and 60 to 95 kg finisher, respectively). The only difference

between diets was the particle size of DDGS and percentage fines in the feed. The grower

diet was fed 18 days while developer and finisher were fed 22 and 76 days, respectively.

Average daily gain (ADG), average daily feed intake (ADFI), and feed to gain (F:G) were

determined at the end of each feeding phase by weighing pigs and measuring feed

disappearance at 0, 18, 40, 83, and 116 d of the test period. Mortality and pig removals were

monitored and recorded twice daily and the BW of pigs that died was used to adjust the F:G.

127


Samples of DDGS were taken as received from the supplier and after further grinding

using a hammermill equipped with 1.6 mm screen and particle size analysis was performed.

Dry sieving according to ASAE method S319.3 (ASABE, 2007) was used to determine the

particle size of DDGS. Particle size analyses were conducted using 14 sieves (U. S. standard

sieve numbers 4, 6, 8, 12, 16, 20, 30, 40, 50, 70, 100, 140, 270) and a pan with the addition

of sieve agitators and 0.5 g of dispersing agent per 100 g of sample (Table 3).

Feed samples were collected during truck loading to calculate the percentage fines

and pellet durability index (PDI). Percentage of fines in each pelleted feed sample was

determined before testing pellets for durability. A US #6 sieve (3.35-mm holes) was used to

sift off the fines from the initial feed sample (~ 5 kg) that contained pellets and fines. The

percentage fines in the feed was calculated as the ratio of the weight of fines obtained after

sample screening relative to the weight of the initial sample using the following formula:

weight of fines/weight of sample × 100.

Pellet durability was determined following the standard method S269.4 of the

American Society of Agricultural Engineers (ASABE, 2007). The standard tumble box

method was the device used to calculate the PDI in accordance with the ASABE

methodology. Four sub-samples of 500 g of whole pellets were placed into each of the 4

compartments of the tumbling box. For the modified method, three hex nuts (50 g/nut) were

added in the tumble box compartment along with the whole pellets in order to increase the

impact forces and improve the ability to predict the true quality of the feed at the farm.

According to Stark (2012), the modified method creates a more aggressive test that is more

128

representative of the impact forces the pellets were exposed to during the manufacturing and

delivery process. The sub-samples were tumbled at 50 rpm for 10 min. After tumbling, each

sub-sample was sifted using a US #6 sieve to remove the fines produced during the tumbling

process and then re-weighed. Pellet durability index was calculated as the ratio of the weight

of the pellets that remained in the sieve after tumbling relative to the initial weight before

tumbling. Every compartment in the tumbling box was swept out by hand after each pellet

durability test in order to remove any fines that accumulated in the corners and avoid cross-

contamination between pellet analyses.


Data were analyzed by analysis of variance using PROC GLM of SAS (SAS Institute,

2006). Pen of pigs was the experimental unit for statistical analysis. Fixed effects included

DDGS particle size (594 and 414 µm), percentage fines in the feed (0 and 25%) and their

interaction. A value of P≤0.05 was considered statistically significant in all tests. Descriptive

statistics are presented in Table 4.



Particle size analyses revealed the particle of DDGS as received and after further

grinding to have an average particle size of 594 µm and 414 µm, respectively. The

percentage pellet fines were 30.8, 28.8, and 33.2% and 12.6, 11.4, and 10.2% for the grower,

developer, and finisher, respectively (Table 5). In the grower feed, there was an interaction of

129

particle size of DDGS and percentage fines on PDI for both the standard and modified PDI

(P≤0.01). When grower diets did not contain added fines in the feed, there were no

differences in PDI among diets that contained DDGS of different grind size, but when

grower diets contained added fines in the feed, the diets that contained the coarse DDGS had

better PDI than further ground DDGS (P≤0.01). The highest PDI was obtained when the

grower diets contained DDGS as received with 25% added fines in the mixer.

The particle size of the DDGS and the percentage fines did not have an influence

(P≥0.05) on PDI for the developer and finisher diets. In contrast, Fahrenholz et al. (2013)

reported an improvement of 1 to 3% for modified PDI when the particle size of DDGS was

reduced from 692 to 508 microns in diets containing 10 to 30% DDGS. In a previous study,

Fahrenholz (2008) reported an increase in standard and modified PDI when previously

pelleted DDGS were further ground. As reported by several authors, decreased particle size

of cereal grains and protein meals have increased pellet quality and reduced the level of

pellet fines (McEllhiney, 1992; Stark, 1994; Wondra et al., 1995a; Chewning, 2010; Pacheco

et al., 2013). According to Behnke (2001), smaller particles have a larger surface area to a

volume ratio and more contact points within the pellet matrix. Therefore, smaller particles

allows heat and moisture to penetrate faster to the center of the particle during feed

conditioning than larger particles, which could lead to increased starch gelatinization and

protein denaturation as well as greater feed ingredient particle agglomeration and binding

(Rosentrater, 2007). Perhaps the differences in the average particle size and particle size

distribution between the DDGS as received from the supplier and further ground (Table 3)

130

were similar and overlapped to a considerable extent, reducing the possibility to obtain

statistical differences in pellet quality.

5.4.2. Swine Performance

Further grinding of DDGS did not improve (P≥0.05) overall ADG, ADFI, or F:G in

grower-finisher pigs. De Jong et al. (2011) reported no differences in overall growth

performance of finishing pigs when DDGS was further ground from 787 to 692 µm using a

roller mill, but they did reported a 1.1% improvement in overall F:G. Previous studies have

reported benefits related to reducing particle size of cereal grains, mainly due to higher

nutrient digestibility. Goodband and Hines (1988) reported greater ADG and improved F:G

in starter pigs when the particle size of barley was reduced from 789 to 676 µm. Healy et al.

(1994) reported a 7% improvement in feed efficiency in starter pigs when the particle size of

corn was reduced from 900 to 500 µm. Wondra et al. (1995a) reported that F:G in finisher

pigs was improved by 8% when the particle size of corn was reduced from 1,000 to 400 µm.

In diets for lactating sows, Wondra (1995b) did not find differences in litter size, pig

survivability, sow weight loss, and sow back fat loss during lactation when the particle size

of the corn was reduced from 1,200 to 400 µm using either hammermill or roller mill, but

litter BW gain increased 11% (46.9 vs. 50.1 kg). There was also a 6% increase in feed intake

as the particle size of the corn was decreased. Lawrence et al. (2003) reported no differences

on ADG or F:G when SBM was further ground. Consequently, Fastinger and Mahan (2003)

suggested that the improvement in F:G when feed ingredients were further ground was likely

131

related to improved starch digestibility and, to a lesser extent due to improved amino acid

digestibility.

In general, ethanol producers have continued to reduce the particle size of the corn

and other cereal grains before the production of ethanol in order to reduce fermentation tank

residence time and to increase the ethanol yield. Kelsall and Lyons (1999) reported that by

reducing the screen size of the hammermill from 8 mm to 5 mm, there was an increase in the

ethanol yield from 2.45 to 2.65 gallons per bushel of corn. In addition, Naidu et al. (2007)

reported a 22% increase in the ethanol concentration when corn was ground using a 0.5 mm

screen in comparison to a 5 mm screen. If the particle size of the initial grain was too large,

there was a reduction in starch gelatinization and enzyme action on the starch was reduced,

which resulted in reduced production of fermentable sugars (Liu, 2011). However, if the

particles were too small, energy expense for grinding increased, the amount of solids in the

thin stillage increased, and centrifuge efficiency decreased (Naidu et al., 2007). The goal of

ethanol producers is to optimize particle grind size of cereal grains in order to maximize

ethanol yield and minimize solids content in the thin stillage.

Removing feed pellet fines did not improve (P≥0.05) overall ADG, ADFI, or F:G of

pigs in comparison to those fed diets that contained at least 25% pellet fines. Stark (1994)

conducted experiments on two nursery diets and one finisher diet to determine the effect of

meal form (pellet or mash) and the percentage pellet fines (0 to 30% fines). In the nursery

diet experiments, there was an improvement in ADG and F:G when pelleted diets were fed,

but the percentage pellet fines did not affect F:G or ADG. In finisher diet experiment,

improved F:G was observed from 2.82 to 2.65 as percentage fines decreased from 60% to

132

0%. Furthermore, Schell and van Heugten (1998) reported improved feed efficiency when

percentage pellet fines decreased from 37% to 3% in grower pigs. Nemechek et al. (2013)

reported feed efficiency was 2.67 to 2.55 for pigs fed 50% and 0% fines, respectively.

Further grinding DDGS did not improve pig performance, likely due to the small difference

in the average particle size and particle size distribution between DDGS as received and after

grinding. The results of this study showed that removing fines produced during the pelleting

process and further grinding DDGS at the feed mill did not improve grower-finisher pig

performance.

133


Table 1. Determined and calculated chemical composition of the distillers dried grain with

solubles (DDGS) (% as-fed basis, unless stated otherwise) as received from the supplier

Item

Determined chemical composition1

Dry matter 88.00

Crude protein 25.34

Ether extract 8.33

Crude fiber 6.35

Ash 4.83

Total calcium 0.20

Total phosphorus 0.77

Available phosphorus 0.56

Gross Energy, kcal/g 4.20

Calculated chemical composition

Metabolizable energy for swine, kcal/kg 3,084.52

Digestible amino acids for swine

Lysine 0.51

Methionine 0.40

TSAA 0.70

Threonine 0.62

Tryptophan 0.16 1In duplicate

134

Table 2. Composition and calculated content of the grower, developer, and finisher diets

(% as fed basis)1

* Diets were fed in pellet form for 116 d. 1 Phase 1 (29 to 40 kg), Phase 2 (40 to 60 kg), Phase 3 (60 to 95 kg). 2 Distillers dried grains with solubles. 3 Vitamin premix provided the following per kg of diet: 6171 IU of vitamin A, 880 IU of vitamin D, 35 IU of vitamin E,

0.02 mg/kg of vitamin B12, 0.18 mg/kg of biotin, 2.91 mg/kg of vitamin K, 4.40 mg/kg of riboflavin, 17.64 mg/kg of

pantothenic acid, 26.45 mg/kg of niacin, 1.32 mg/kg of folate. 4 Mineral premix provided the following per kg of diet: 16.5 mg/kg of Cu, 165.3 mg/kg of Fe, 39.60 mg/kg of Mn, 165.30

mg/kg of Zn, 0.30 mg/kg of I, 0.30 mg/kg of Se. 5 Selenium premix provided 0.2 mg/kg Se. 6 Chlortetracycline was included at 440 mg/kg (CTC 100, Zoetis, Florham Park, NJ) 7 Tiamulin hydrogen fumarate was included at 38.5 mg/kg (Denagard 10, Novartis Animal Health, Larchwood IA) 8 Virginiamycin was included at 5.5 mg/kg (Stafac 20, Phibro Animal Health, Ridgefield Park, NJ) 8 Bambermycin was included at 2.2 mg/kg (Flavomycin 4, Huvepharma Inc., Peachtree City, GA)

Item1 Grower Developer

Finisher

Grower 1 Grower 2

Ingredient ———————————————— (%) ——————————————

Corn 45.17 45.02 48.02 52.99

Soybean meal (48% CP) 15.50 15.45 12.90 8.05

DDGS2 30.00 30.00 30.00 30.00

Poultry fat 6.50 6.50 6.50 6.50

Limestone 1.57 1.56 1.67 1.67

Salt 0.35 0.35 0.35 0.35

Vitamin premix3 0.03 0.03 0.03 0.02

Mineral premix4 0.05 0.05 0.05 0.05

L-Lysine-HCl 0.40 0.40 0.37 0.30

L-Threonine 0.08 0.08 0.06 0.01

Selenium premix5 0.03 0.03 0.03 0.03

CTC 1006 0.00 0.20 0.00 0.00

Denagard 107 0.18 0.18 0.00 0.00

Stafac 207 0.00 0.00 0.00 0.01

Flavomycin 48 0.00 0.00 0.03 0.00

Phytase 0.01 0.01 0.01 0.01

Synthetic Red 0.15 0.15 0.00 0.00


ME, kcal/kg 3504.14 3497.69 3512.92 3515.95

Crude protein 18.86 18.83 17.79 15.74

Calcium 0.67 0.66 0.70 0.70

Phosphorus 0.44 0.44 0.43 0.41

Lysine 1.15 1.14 1.05 0.87

TSAA 0.67 0.66 0.64 0.59

Threonine 0.77 0.77 0.72 0.59

Tryptophan 0.19 0.19 0.17 0.15

135

Table 3. Particle size distribution of the distillers dried grain with solubles (DDGS) used during the experiment

Particle Size of the DDGS

Lot #1 Lot #2 Lot #3 Lot #4

U. S. Sieve Sieve Size Coarse Fine Coarse Fine Coarse Fine Coarse Fine

Retained on sieve Retained on sieve Retained on sieve Retained on sieve

# µm % % % % % % % %

4 4760 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

6 3360 0.07 0.00 0.12 0.00 0.19 0.00 0.00 0.00

8 2380 0.08 0.00 0.20 0.00 0.37 0.00 0.05 0.00

12 1680 1.77 0.00 1.50 0.00 1.30 0.09 1.91 0.00

16 1190 14.68 0.39 13.90 0.30 2.88 0.38 17.50 0.67

20 840 22.55 11.50 21.90 11.30 4.84 2.18 22.32 13.71

30 590 25.26 30.43 24.50 30.10 13.12 11.74 20.51 24.83

40 420 19.39 27.71 20.10 28.30 21.77 22.63 16.49 22.15

50 297 9.11 14.80 9.90 18.30 23.44 25.19 9.95 15.63

70 210 3.32 6.36 3.70 8.40 15.26 17.23 4.93 10.64

100 149 1.52 3.49 1.30 2.60 8.65 10.04 2.11 3.93

140 105 0.83 2.34 0.90 2.00 5.67 6.82 1.61 3.45

200 74 0.41 1.06 1.10 1.80 1.86 2.56 1.11 2.49

270 53 0.44 1.17 0.70 1.30 0.37 0.85 0.70 1.25

Pan 37 0.56 0.74 0.60 0.80 0.28 0.28 0.80 1.25

Average, µm 682.0 418.0 655.0 467.0 383.0 330.0 653.0 439.0

SD 1.83 1.81 1.89 1.82 1.93 1.79 2.01 1.98

136

Table 4. Descriptive statistics for pellet quality

Item No. of batches Mean Standard deviation

—————————— (%) ——————————

Pellet fines1 44 20.3 11.6

Standard pellet durability index (PDI)2 44 98.5 0.5

Modified pellet durability index(PDI)3 44 80.6 5.1 1 Pellet fines = (weight of fines/weight of initial sample) x 100 2 Standard PDI = (weight of fines/weight of initial sample) x 100 after tumbling 500 g of whole pellet at 50 rpm

for 10 min 3 Modified PDI = (weight of fines/weight of initial sample) x 100 after tumbling 500 g of whole pellet at 50 rpm

for 10 min with the addition of 3 hex nuts (50 g/nut)

137

Table 5. Effect of the particle size of distillers dried grain with solubles (DDGS) on percentage fines and standard and modified

pellet durability index (PDI)

DDGS

Particle Size1

Percentage

Fines1

Percentage Fines

Standard PDI

Modified PDI

Grower Developer Finisher Grower Developer Finisher Grower Developer Finisher

(%) —————— (%) —————— —————— (%) —————— —————— (%) ——————

Coarse 19.46 11.35 10.16a 98.30 98.75 98.38 82.73 82.45 76.56

Fine 23.52 12.50 5.64b 98.85 98.65 98.68 79.75 81.83 78.30

SEM 5.08 3.14 1.48 0.19 0.18 0.17 1.03 1.20 1.76

0 12.60b 11.35B 10.16B 98.30b 98.75 98.38 79.95 82.45 76.56

25 30.38a 28.83A 33.20A 99.00a 98.83 97.94 82.53 84.40 78.20

SEM 5.08 3.14 1.48 0.19 0.18 0.17 1.03 1.20 1.76

Coarse 0 14.43 11.35 10.16 98.30B 98.75 98.38 78.85b 82.45 76.56

Fine 0 10.77 12.50 5.64 98.85A 98.65 98.68 81.05b 81.83 78.30

Coarse 25 24.49 28.83 33.20 99.00A 98.83 97.94 86.60a 84.40 78.20

Fine 25 36.27 33.05 26.35 98.10B 98.40 98.42 78.45b 84.68 79.94

SEM 5.08 3.14 1.48 0.19 0.18 0.17 1.03 1.20 1.76

Source of variation ——————————————————— P-value ———————————————————

DDGS particle size 0.637 0.800 0.047 0.062 0.774 0.081 0.157 0.715 0.489

Fines in feed 0.023 0.002 0.001 0.022 0.702 0.229 0.002 0.259 0.514

DDGS particle size x percentage fines 0.204 0.634 0.443 0.002 0.383 0.607 0.003 0.710 1.000 a-b Means with different superscripts in the same column differ significantly (P ≤ 0.05). A-B Means with different superscripts in the same column differ significantly (P ≤ 0.01). 1 Percentage fines was calculated during truck unloading as = (weight of fines/weight of the sample) x 100 2 Standard PDI = (weight of fines/weight of initial sample) x 100 after tumbling 500 g of whole pellets at 50 rpm for 10 min 3 Modified PDI = (weight of fines/weight of initial sample) x 100 after tumbling 500 g of whole pellets at 50 rpm for 10 min with the addition of 3 hex nuts

(50g/nut)

138

Table 6. Descriptive statistics for pig live performance1

Feeding Phase

Grower Developer Finisher Total

Average Daily Gain

————————————————————— (kg) —————————————————————

0-18 d 19-40 d 41-83 d 84-116 d 0-116 d

0.77±0.072 0.90±0.08 0.81±0.07 0.87±0.09 0.84±0.04

Feeding Phase


Average Daily Feed Intake

————————————————————— (kg) —————————————————————

0-18 d 19-40 d 41-83 d 84-116 d 0-116 d

1.40±0.14 1.87±0.20 2.26±0.23 2.80±0.18 2.22±0.16

Feeding Phase


Feed:Gain3

——————————————————— (kg:kg) ———————————————————

0-18 d 19-40 d 41-83 d 84-116 d 0-116 d

1.82±0.18 2.09±0.15 2.78±0.20 3.23±0.31 2.62±0.13 1 A total of 760 (initial BW, 28.8±3.1 kg), with 19 pigs per pen and 10 pens per treatment

2 Standard error of the mean (n = 40). 3 Feed:Gain (F:G) = Total pen BW gain/feed intake per pen, including BW of mortality that occurred during

each time period.

139


percentage pellet fines on body weight of grower-finisher pigs1

DDGS

Particle Size2

Feed

Fines2

Body Weight

0 d 18 d 40 d 83 d 116 d

(µm) (%) —————————— (kg) ——————————

Main effects

Coarse 28.9 40.2 59.6 94.9 123.9

Fine 28.5 40.2 60.3 95.7 124.3

SEM 0.7 1.4 1.6 2.0 1.8

0 28.8 40.1 59.9 95.4 124.4

25 28.5 40.2 60.0 95.1 123.8

SEM 0.7 1.4 1.6 2.0 1.8

Interaction effects

Coarse 0 28.6 40.2 59.4 94.7 123.2

Coarse 25 29.2 40.3 59.8 95.0 124.7

Fine 0 29.0 40.1 60.4 96.2 125.6

Fine 25 27.9 40.2 60.2 95.2 123.0

SEM 1.0 2.0 2.3 2.8 2.5

Source of variation ————————— P-value —————————

DDGS particle size 0.463 0.979 0.776 0.765 0.677

Feed fines 0.656 0.964 0.971 0.917 0.969

DDGS particle size x feed fines 0.129 0.993 0.905 0.812 0.577 a-c Means with different superscripts in the same column differ significantly (P ≤ 0.05). 1 A total of 760 (initial BW, 28.8 kg), with 19 pigs per pen and 10 pens per treatment. 2 Treatments consisted of two DDGS particle sizes coarse and fine and two percentages of pellet fines (0 and

25% fines).

140

Table 8. Effect of the particle size of distillers dried grains with solubles (DDGS) and percentage pellet fines on average daily

gain, average daily feed intake, and feed:gain of grower-finisher pigs1

DDGS

Particle Size

Feed

Fines

Average Daily Gain Average Daily Feed Intake Feed:Gain

1-18 d 19-40 d 41-83 d 84-116 d Total 1-18 d 19-40 d 41-83 d 84-116 d Total 1-18 d 19-40 d 41-83 d 84-116 d Total

(µm) (%) —————— (g) —————— —————— (g) —————— —————— (g:g) ——————

Main Effects

Coarse 779 876 810 869 836 1403 1854 2229 2783 2205 1.81 2.12 2.76 3.23 2.64

Fine 762 909 811 871 842 1375 1874 2264 2793 2222 1.81 2.06 2.79 3.23 2.64

SEM 32 27 32 36 18 54 50 77 77 54 0.07 0.05 0.06 0.10 0.03

0 778 892 816 873 843 1404 1860 2269 2788 2224 1.81 2.09 2.78 3.22 2.64

25 763 893 805 867 835 1375 1868 2224 2788 2204 1.81 2.09 2.77 3.24 2.64

SEM 32 27 32 36 18 54 50 77 77 54 0.07 0.05 0.06 0.10 0.03

Interaction effects

Coarse 0 794 865 806 862 833 1437 1830 2245 2748 2201 1.81 2.12 2.79 3.22 2.64

Coarse 25 764 887 814 877 840 1370 1879 2213 2819 2210 1.81 2.12 2.72 3.23 2.63

Fine 0 761 919 827 885 854 1372 1891 2293 2829 2247 1.80 2.06 2.77 3.22 2.63

Fine 25 762 899 795 857 830 1379 1857 2235 2757 2197 1.81 2.06 2.82 3.24 2.65

SEM 44 40 46 52 23 77 68 107 106 77 0.10 0.07 0.09 0.15 0.05

Source of variation ——————————————————————————————————— P-value ———————————————————————————————————

DDGS particle size 0.441 0.107 0.956 0.941 0.652 0.465 0.564 0.519 0.854 0.664 0.998 0.121 0.471 0.972 0.951

Feed fines 0.514 0.971 0.610 0.804 0.480 0.438 0.832 0.410 0.995 0.598 0.919 0.960 0.824 0.812 0.978

DDGS particle size x feed fines 0.492 0.305 0.381 0.420 0.190 0.335 0.233 0.814 0.184 0.450 0.948 0.928 0.216 0.932 0.582

a-c Means with different superscripts in the same column differ significantly (P ≤ 0.05). 1 A total of 760 (initial BW, 28.8 kg), with 19 pigs per pen and 10 pens per treatment. 2 Treatments consisted of two DDGS particle sizes coarse and fine and two percentages of pellet fines (0 and 25% fines). 3 FCR = Feed intake per pen/total pen BW gain, including BW of mortality that occurred during each time period.

141

5.6. REFERENCES

Abdollahi, M. R., V. Ravindran, T. J. Wester, G. Ravindran, and D. V. Thomas. 2011.

Influence of feed form and conditioning temperature on performance, apparent

metabolisable energy and ileal digestibility of starch and nitrogen in broiler starters

fed wheat-based diet. Anim. Feed Sci. Technol. 168:88-99.



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Behnke, K .C. 1996. Feed manufacturing technology: current issues and challenges. Anim.

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Behnke, K. C., and R. S. Beyer. 2002. Effect of feed processing on broiler performance. VIII

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form on broiler performance. M.S. Thesis. North Carolina State University, Raleigh,

NC.

Cook, D., N. Paton, and M. Gibson. 2005. Effect of dietary level of distillers dried grains

with solubles (DDGS) on growth performance, mortality, and carcass characteristics

on grow-finish barrows and gilts. J. Anim. Sci. 83 (Suppl. 1):335 (Abstr.).

DeDecker, J. M., M. Ellis, B. F. Wolter, J. Spencer, D. M. Webel, C. R. Bertelsen, and B. A.

Peterson. 2005. Effects of dietary level of distillers dried grains with solubles and fat

on the growth performance of growing pigs. J. Anim. Sci. 83 (Suppl. 2):79 (Abstr.).

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DeJong, J. A., S. S. Dritz, M. D. Tokach, J. M. DeRouchey, J. L. Nelssen, and R. D.

Goodband. 2011. Effect of regrinding dried distillers grains with solubles on finishing

pig growth performance. Pages 197-201 in Finishing nutrition and management.

Kansas Swine Industry Day Report of Progress. Manhattan, KS.

Fahrenholz, A. C. 2008. The effects of DDGS inclusion on pellet quality and pellet mill


Fahrenholz, A. C., K. C. Behnke, L. J. McKinney. 2013. Processing of pelleted feeds using

pelleted DDGS as an ingredient. Appl. Eng. Agric. 29:89-92.



Frikha, M., H. M. Safaa, M. P. Serrano, X. Arbe, and G. G. Mateos. 2009. Influence of the

main cereal and feed form of the diet on performance and digestive tract of brown-

egg laying pullets. Poult. Sci. 88:994-1002.

Goodband, R. D., and R. H. Hines. 1988. An evaluation of barley in starter diets for swine. J.

Anim. Sci. 66:3086-3091.




Healy, B. J., J. D. Hancock, G. A. Kennedy, P. J. Bramel-Cox, K. C. Behnke, and R. H.

Hines. 1994. Optimum particle size of corn and hard and soft sorghum for nursery

pigs. J. Anim. Sci. 72: 2227-2236.

Jensen, L. S. 2000. Influence of pelleting on the nutritional needs of poultry. Asian Austral. J.

Anim. Sci. 13:35-46.

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Kelsall, D. R., and T. P. Lyons. 1999. Grain dry milling and cooking for alcohol production:

designing for 23% ethanol and maximum yield. Chapter 2 in The Alcohol Textbook.

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ed. Jacques, K. A., T. P. Lyons, and D. R. Kelsall. Eds. Nottingham University

Press, Nottingham, UK.

Lawrence, K. R., C. W. Hastad, R. D. Goodband, M. D. Tokach, S. S. Dritz, J. L. Nelssen, J.

M. DeRouchey, and M. J. Webster. 2003. Effects of soybean meal particle size on

growth performance of nursery pigs. J. Anim. Sci. 81:2118-2122.

Liu, K. 2011. Chemical composition of DDGS. Pages 143-178 in Distillers Dried Grains:

Production, Properties, and Utilization. Liu, K. S., and K. A. Rosentrater. Eds. CRC

Press, Boca Raton, FL.

McEllhiney, R. 1992. What is the optimum particle size for pelleting? Feed Management

9:19-23.

Myers, A. J., R. D. Goodband, M. D. Tokach, S. S. Dritz, J. M. DeRouchey, and J. L.

Nelssen. 2013. The effects of diet form and feeder design on the growth performance

of finishing pigs. J. Anim. Sci. 91:3420-3428.

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ground corn particle size on ethanol yield and thin stillage soluble solids. Cereal

Chem. 84:6-9.

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Nelssen. 2013. Effect of pellet quality and feeder adjustment on growth performance

on finishing pigs. J. Anim. Sci. 91 (Suppl. 2):69.

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development. Poult. Sci. 92:2914-2922.

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of grower pigs. J. Anim. Sci. 76 (Suppl. 1):185.

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Rosentrater, K. A. 2007. Can we really pellet DDGS. Distillers Grains Quarterly. 3:16-21.

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145

CHAPTER VI

INTEGRATION OF CONCEPTS AND FINDINGS FROM RESEARCH STUDIES

146

6.1. INTRODUCTION

Feed costs represent a significant fraction of the total production costs in swine and

poultry farming. Therefore, producers are constantly evaluating ways to reduce feed costs

and improve live performance and feed efficiency (Myers et al., 2013), either by changing

feed processing techniques, such as pelleting or particle size manipulation, or by including

alternative ingredients (Stein and Shurson, 2009), such as distiller dried grains with solubles

(DDGS). Currently, DDGS are frequently used as a source of protein, energy, and

phosphorus in poultry and swine diets and replace some of the more expensive dietary

ingredients, such as corn, SBM, and dicalcium phosphate. However, the usage of DDGS has

created new challenges associated with nutrient variability, particularly amino acid

digestibility, and feed-processing challenges related to decreased pellet quality and feed mill

throughput (Behnke, 2007). Reducing DDGS particle size may be a strategy to increase the

dietary inclusion of DDGS without adversely affecting pellet quality and/or animal

performance.

The following hypothesis was tested in this dissertation: the benefit of dietary

inclusion of DDGS depends upon feed formulation strategies and particle size manipulation

that could influence pellet durability, nutrient digestibility, and overall live performance of

poultry and swine. Certain experiments described in the previous chapters have been

designed to understand the effects of different inclusions levels of DDGS in broiler diets

based on various formulation strategies. In addition, it was determined important to test the

influence of the analytical methodology to measure crude fat content of DDGS on pellet

quality and broiler performance. The influence of the percentage fines in pelleted feed and

147

particle size of DDGS on broiler and swine performance was also measured. Understanding

the effects of dietary inclusion of DDGS on pellet quality and broiler performance, and the

influence of the particle size and percentage fines on broiler and grower-finisher swine

performance would allow us to take a better advantage of a feed ingredient that will continue

to be available as a co-product of the ethanol production.

We demonstrated that adjustments in feed processing and feed formulation could be

made to improve the utilization of DDGS in broiler and swine diets. The objectives of the

present chapter are as follows: 1) to summarize the most important findings of the research

studies; 2) to discuss the influence of dietary DDGS inclusion and particle size on pellet

quality on the growth performance of broilers and grower-finisher swine; and 3) to suggest

recommendations regarding the maximum dietary inclusion of DDGS in broiler diets based

on various formulation strategies.

6.2. EFFECTS OF DDGS INCLUSION ON PELLET QUALITY

The inclusion of DDGS produced diverse results in swine and broiler diets. As

reported in Chapter II, swine finisher diets containing 30% DDGS had better pellet quality,

as measured by pellet durability index (PDI), than diets that did not contain DDGS. However

in the broiler trials (Chapters III and IV), PDI was observed to decrease as the inclusion of

DDGS increased from 0 to 30% or from 15 to 30%. The decreased PDI in the broiler trials

was confounded by a greater amount of fat added in the mixer prior to pelleting due to the

lower metabolizable energy in DDGS as compared to corn or SBM. Based on the results

obtained from these trials, we concluded that decreased pellet quality in broiler diets

148

containing DDGS was due to: 1) the protein in DDGS becoming denatured by heat

processing during the drying process and likely by alcohol during the fermentation process

such that it was no longer functional as a pellet binder during particle agglomeration or

pelleting; and 2) diets with greater inclusion of DDGS usually contained a higher amount of

added fat prior to pelleting. Fat has been reported to increase lubrication, reduce frictional

heat between the feed and the pellet die wall, and hence reduced starch gelatinization and

binding at the surface of the pellet. Obviously, we could not control the degree of protein

denaturation of DDGS during drying or the quantity of starch before it arrived to the feed

mill. But the amount of added fat in the mixer prior to pelleting could be the most practical

alternative to maintain pellet durability in diets containing DDGS.

6.3. EFFECTS OF FURTHER GRINDING DDGS ON PELLET QUALITY AND

BROILER AND SWINE PERFORMANCE

As observed in the experiment with finisher pigs diets (Chapter II) and broilers diets

(Chapter III), further grinding of DDGS after it was received at the feed mill did not have a

positive effect on pellet durability. The main purpose of particle size reduction is to increase

relative surface area and create more contact points per unit volume within the pellet matrix

(Behnke, 2001). Therefore, particle size has had a significant influence on pellet durability

and, generally finer particles have resulted in higher pellet durability (Behnke, 1994; Kaliyan

and Morey, 2009). In addition, fine particle size of cereal grains has been reported to improve

live performance and feed efficiency in nursery and growing-finishing pigs (Healy et al.,

1994) by increasing the surface area of the digesta available for interaction with digestive

149

enzymes, thus allowing digestive enzymes to release nutrients more effectively (Goodband et

al., 2002; Fastinger and Mahan, 2003). In these trials, further grinding of DDGS produced a

trend towards decreased pellet quality. The explanation was that grinding DDGS with

approximately 9.8% crude fat could have released fat previously stored in the protein matrix

(T. Winowiski, personal communication, August, 2013), which impeded particle size

agglomeration during pelleting. Fat has been reported to work as a lubricant during the

pelleting process (Stark, 1994; Thomas et al., 1998; Cutlip et al., 2008). In addition, being

hydrophobic, fat has reduced the binding properties of water-soluble nutrients such as

protein, starch, and fiber (Thomas et al., 1998). In Chapter III, further grinding of DDDS

resulted in greater feed consumption and BW of broilers from 1-42 d of age than birds fed

DDGS as received, but no differences were observed for FCR. However, further grinding of

DDGS did not impact average daily gain (ADG), average daily feed intake (ADFI), or feed

to gain (F:G) of grower-finisher pigs.

In general, the average particle size and particle size distribution between the DDGS

as received at the feed mill and the particle of the DDGS after grinding, using a 1.6 mm

hammer mill screen, was similar and overlapped to a considerable extent in these

experiments (see figures in previous chapters). Ethanol producers have reduced the particle

size of the corn and other cereal grains in order to reduce the fermentation time and increase

ethanol yield. Based on the results of these studies, we concluded that DDGS did not need to

be further ground at the feed mill, as it did not improve pellet quality or overall poultry and

swine feed efficiency.

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6.4. EFFECT OF PERCENTAGE PELLET FINES ON BROILER AND SWINE LIVE

PERFORMANCE

The percentage feed fines did not affect feed intake in broilers and swine (Chapter III,

and V). In previous broiler studies, feed consumption has been observed to decrease as the

percentage fines in pelleted feed increased (Cutlip et al., 2008). This reduction in feed

consumption of pelleted feed with a high percentage fines has been associated with

flowability problems at the feeder and limited access to ad libitum feed consumption.

However, in our broiler studies, feeders were shaken three times daily after 14 d of age in

order to keep access to feed available at all times. In the swine study, the use of an automatic

feeder provided the opportunity to add feed at multiple times daily, which stimulated feed

intake because there was fresh feed in front of the pigs at all times, regardless of the

percentage feed fines. Broilers and grower-finisher pigs fed diets that contained 25% fines

exhibited a live performance similar to broiler or pigs fed diets with 0% fines. However,

broilers fed diets with 50% fines exhibited a lower BW than birds fed diets with 0% feed

fines. Stark (1994) reported that feeding pigs pelleted diets that contained 60% fines

produced a FCR similar to feeding mash diets and concluded that feed with a high percentage

fines diminished the benefits of pelleting. According to Stark (2012), integrated operations

do not remove the fines produced during the pelleting process and feed can contain 10 to

50% fines by the time it is finally delivered to the feeders at the farm. Based on both studies,

we concluded that with appropriate feeder management, up to 25% feed fines could be fed

without a negative effect on BW and feed efficiency. Nutritionists, feed mill managers, and

purchasing agents could use the data obtained from our research trials to make decisions

151

during ingredient procurement and/or feed manufacturing that would allow them to reduce

overall feed and/or feed manufacturing costs.

6.5. MAXIMUM INCLUSION OF DDGS BASED UPON FORMULATION

STRATEGIES

In general, DDGS have been reported to contain lower amino acid digestibility than

corn and SBM. The temperatures applied during the drying process of DDGS have been

reported to decrease protein quality and reduce digestibility of certain amino acids (Noll et

al., 2001; Fastinger and Mahan, 2006; Stein et al., 2006; Pahm et al., 2008). The free amino

group of lysine may react with reducing sugars in the presence of heat, and causes the

formation of undigestible complexes (Cromwell et al., 1993; Spiehs et al., 2002; Batal and

Dale 2006; Parsons et al., 2006; Fontaine et al., 2007). In Chapter III, broiler diets were

formulated on a digestible amino acid basis to account for the differences in amino acid

digestibility between DDGS, corn, and SBM. In this trial, no differences in BW or nitrogen

digestibility were observed when diets contained either 15 or 30% DDGS. The results of this

study indicated that up to 30% DDGS could be fed in broiler diets from 1-42 d of age if diets

were formulated on a digestible amino acid basis.

In the subsequent trial (Chapter IV), diets were formulated on a total amino acid basis

and this trial demonstrated that birds fed the control diet without DDGS or 15% DDGS had a

greater BW than birds fed the diets containing 30% DDGS at 35 d of age. Furthermore, birds

fed diets without DDGS weighed more at 49 d of age than birds fed diets containing 15 or

30% DDGS. The greater BW was not related to increased feed consumption, but instead

152

associated with improved FCR. In addition, birds fed diets without DDGS or 15% DDGS had

greater nitrogen digestibility during the grower (15-35 d) and finisher (36-49 d) periods than

birds fed diets containing 30% DDGS, and they had a lower incidence of footpad lesions.

Given that lysine was the most susceptible amino acid to heat damage, and since poultry do

not possess enzymes that would break the lysine-sugar complex bond, heat damaged lysine is

typically rendered nutritionally unavailable (Batal and Bregendahl, 2011). Therefore, we

concluded that the maximum dietary inclusion of DDGS would depend upon formulation

strategies, and the usage of the digestible amino acid methodology warranted a higher

inclusion of DDGS. Distiller dried grains will continue to be available as a co-product of

ethanol industry. Therefore, adjustments in feed processing and feed formulation will need to

be made in order to improve DDGS utilization in poultry and swine diets. Once this has been

done, the decisions regarding DDGS usage in poultry and swine diets will depend upon

economic return alone.

153

6.6. REFERENCES

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Cromwell, G. L., K. L. Herkelman, and T. S. Stahly. 1993. Physical, chemical, and

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154




Healy, B. J., J. D. Hancock, G. A. Kennedy, P. J. Bramel-Cox, K. C. Behnke, and R. H.

Hines. 1994. Optimum particle size of corn and hard and soft sorghum for nursery

pigs. J. Anim. Sci. 72:2227-2236.

Kaliyan, N., and R. V. Morey, 2009. Factors affecting strength and durability of densified

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Nelssen. 2013. The effects of diet form and feeder design on the growth performance

of finishing pigs. J. Anim. Sci. 91:3420-3428.

Noll, S., V. Stangeland, G. Speers, and J. Brannon. 2001. Distillers grains in poultry diets.

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Minnesota Nutr. Conf. and Minnesota Corn Growers Assn.

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Pahm, A. A., C. Pedersen, D. Hoehler, and H. H. Stein. 2008. Factors affecting the variability

in ileal amino acid digestibility in corn distillers dried grains with solubles fed to

growing pigs. J. Anim. Sci. 86:2180-2189.

Parsons, A. S., N. Buchanan, K. Blemings, M. Wilson, and J. Moritz. 2006. Effect of corn

particle size and pellet texture on broiler performance in the growing phase. J. Appl.

Poult. Res. 15:245-255.

Spiehs, M. J., M. H. Whitney, and G. C. Shurson. 2002. Nutrient database for distillers dried






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digestibility in ten samples of distillers dried grain with solubles by growing pigs. J.

Anim. Sci. 84:853-860.

Stein, H. H., and G. C. Shurson. 2009. Board invited review: The use and application of

distillers dried grains with solubles (DDGS) in swine diets. J. Anim. Sci. 87:1292-

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Thomas M., T. van Vliet, and A. F. B. van der Poel. 1998. Physical quality of pelleted animal

feed. 3. Contribution of feedstuff components. Anim. Feed Sci. Technol. 76:59-78.

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