Genetic gain in open nucleus breeding scheme to improve milk production in Egyptian Buffalo

1Sameh Abdel-Salam, ICAR 2010

GENETIC GAIN IN OPEN NUCLEUS BREEDING SCHEME TO IMPROVE MILK TO IMPROVE MILK PRODUCTION IN EGYPTIAN BUFFALOS.A. Abdel-SalamFaculty of Agriculture, Cairo University, Egypt3/6/2010

INTRODUCTIONINTRODUCTION2

FAOSTAT (2009) the Egyptian buffalo contributes about

2.7% and 8.4% to the world buffalo's milk and meat.2.7% and 8.4% to the world buffalo s milk and meat.

The proportion of Egyptian buffaloes to the world

buffalo’s milk production decreases year after year.

The increase of total milk production of Egyptian

buffaloes was due only to increasing buffalobu a oes as ue o y o c eas g bu a o

population size.

3/6/2010Sameh Abdel-Salam, ICAR 2010


Livestock production in developing regions is

generally characterized by small herd sizegenerally characterized by small herd-size,

uncontrolled mating, and the absence of pedigreeg p g

and performance recording.

These characteristics limit the implementation of

effective genetic improvement programs.



To overcome these problems, nucleus breeding

schemes have been suggested in which geneticschemes have been suggested, in which genetic

improvement is centrally organized in a population

maintained in research institutes or government farms.

The open nucleus breeding scheme offers a simpler

procedure for producing and disseminating breedingprocedure for producing and disseminating breeding

stock of known value.



The establishment of two-tier open nucleus breeding

system to maximize genetic improvement, reduce

inbreeding rate and reduce the total cost of recording

in smallholder systemin smallholder system.

Several of studies indicated the significance of using

open nucleus breeding scheme to improve milk

production of buffalo and increase the rate of geneticproduction of buffalo and increase the rate of genetic

gain.



The purpose of this paper was to use the simulation

t h i t t d th t d ti i btechnique to study the expected genetic gain by

changing migration rates and male selectiong g g

intensity in four generations of applying two-tier

open nucleus breeding scheme to improve milk

production of Egyptian buffaloes using different

l d l ti inucleus and population sizes.3/6/2010Sameh Abdel-Salam, ICAR 2010

MATERIAL AND METHODS7


Basic parametersBasic parameters

The estimates used in generating the simulated populations8

The estimates used in generating the simulated populations

Parameter Estimate Reference

Average total milk yield (TMY) 1884, kg CISE, 2007

Phenotypic variance for TMY 191845, kg2 CISE, 2007

Phenotypic standard deviation for TMY 438, kg CISE, 2007Phenotypic standard deviation for TMY 438, kg CISE, 2007

Average generation interval 5.78, yr Mourad, 1990

Heritability estimate 0.17 CISE, 2007

CISE: Cattle Information Systems/Egypt3/6/2010Sameh Abdel-Salam, ICAR 2010

Calculation of the expected genetic gain in ilk i ldmilk yield

I t i bl f l l ti ti i 9

Input variables for calculating genetic gain Item Description Symbol Value

H i bili i h2 0 17Heritability estimate h2 0.17Replacement rate r 0.20Fraction of total population in nucleus p 0.05, 0.10Fraction of nucleus dams born in base x 0 50Fraction of nucleus dams born in base x 0.50Fraction of base dams born in nucleus y 0.08, 0.14, 0.17

Fraction of nucleus sires born in base v 0.00

F ti f b i b i l 0 10 0 20 0 30 0 60 1 00Fraction of base sires born in nucleus w 0.10, 0.20, 0.30, 0.60, 1.00

Proportion of all males born used as sires a 0.05, 0.10, 0.20

Proportion of all females born used as dams b 0.80Si l d l i i ( b f b d bl f l ) 2 Simulated population size (number of breedable females) z 10000, 25000, 50000, 100000Generations G 1, 2, 3, 4


S f b di h d Structure of breeding scheme and gene migration

10g


The effects of the different variables on genetic gain were analyzed according to the following model:

GGijklmnop=µ+Gi+zj+pk+al+MRm+wn+yo+eijklmnopijklmnop µ i j pk l m n yo ijklmnop

where GG is the genetic gain of milk yield, µ is the average genetic gain of milk yield, Gi is the number of average genetic gain of milk yield, Gi is the number of generation (4 level), zj is the population size (4 level), pk is the fraction of total population in nucleus (2 pk is the fraction of total population in nucleus (2 levels), al is the proportion of all males born used as sires (3 levels), MR is the mating ratio (6 levels), wsires (3 levels), MRm is the mating ratio (6 levels), wnis the fraction of base sires born in nucleus (5 levels), y is the fraction of base dams born in nucleus (3 yo is the fraction of base dams born in nucleus (3 levels) and eijklmnop is the residual term.

3/6/201011

Sameh Abdel-Salam, ICAR 2010

RESULTS AND DISCUSSION12


cd

b

a

a,b,c,dMeans with different letters differ significantly (P<0.05).13

Change of genetic gain means by generation number.


450

n, k

g

d

410

430

etic

Gai

n

b

c

d

390n

of G

ene

a

350

370

Mea

n

10000 25000 50000 100000

Population Size (z)

a,b,c,dMeans with different letters differ significantly (P<0.05).14

Change of genetic gain means by changing population size (z).


Least squares mean and standard errors (SE) of genetic gain ofilk i ld (k ) i i l d b ff l l i f diffmilk yield (kg) in simulated buffalo populations of different

nucleus sizes (p)

p Mean SE

0.05 397a 70.10 415b 6

a,bMeans with different letters differ significantly (P<0.05)15


405

406

, kg

a

404

405

etic

Gai

n

a

402

403of

Gen

ea

400

401

Mea

n

4000.05 0.10 0.20

Proportion of all males born used as sires (a)

aMeans with same letters do not differ significantly (P>0.05).

p ( )

16

Change of genetic gain means by changing proportion of all males born used as sires (a).


500

400

450

Gai

n, k

g d

350

400

Gen

etic

Gab

bc

250

300

Mea

n of

G aab

2500.1 0.2 0.3 0.6 1.0

Fraction of base sires born in nucleus (w)

M

a,b,c,dMeans with different letters differ significantly (P<0.05).

Fraction of base sires born in nucleus (w)

17

Change of genetic gain means by changing fraction of base sires born in nucleus (w).


500

kg

d d d

400

450

tic G

ain,

k

c

350

400

of G

enet

b

250

300

Mea

n a

2501:25 1:50 1:100 1:1000 1:2500 1:5000

Mating ratio (male: female)

a,b,c,dMeans with different letters differ significantly (P<0.05).

g ( )

18

Change of genetic gain means by changing different mating ratios (MR).


450

n, k

g

430

440

etic

Gai

n b

410

420n

of G

ene

aa

390

400

Mea

n a

3900.08 0.14 0.17

Fraction of base dams born in nucleus (y)

a,bMeans with different letters differ significantly (P<0.05).19

Change of genetic gain means by changing fraction of base dams born in nucleus (y).


CONCLUSIONCONCLUSION20

The open nucleus breeding scheme offers a suitable

practical procedure for producing and disseminating practical procedure for producing and disseminating

buffalo bulls of known breeding values.

Applying ONBS for many generations of selection

could accelerate the rate of genetic gain of milk

d ti i b ff l d i th ilk production in buffalo and increase the average milk

yield by 15% in G1 to 26% in G4. y y


CONCLUSIONCONCLUSION21

It is recommended to take into account mating

ti h l i ONBS ith th bi ti ratios when applying ONBS with the combinations

of z (population size) and p (nucleus size) which (p p ) p ( )

affect a (proportion of all males born used as sires)

and w (fraction of base sires born in nucleus).


Sameh Abdel-Salam, ICAR 2010 22

3/6/2010

Genetic gain in open nucleus breeding scheme to improve milk production in Egyptian Buffalo

Documents

Transcript of Genetic gain in open nucleus breeding scheme to improve milk production in Egyptian Buffalo