Fatty Acid Composition and Lipid and Protein Oxidation Products in Muscles of Broilers Fed with...

Arch.Geflügelk., 76 (4). S. 259–269, 2012, ISSN 0003-9098. © Verlag Eugen Ulmer, Stuttgart

Fatty acid composition and lipid and protein oxidation products in muscles of broilers fed with different plant oils*

Fettsäuremuster und Lipid- sowie Proteinoxidationsprodukte in Muskeln von Broilern, die mit Rationen mit unterschiedlichen Pflanzenölen gefüttert wurden

Gordana Kralik1, Valentina Pavić2, Dalida Galović1, Z. Škrtić1, Zlata Kralik1 and Elizabeta Has-Schön2

1 Dept. of Animal Husbandry, Faculty of Agriculture, University J.J. Strossmayer,Osijek, Croatia2 Dept. of Biology, University J.J. Strossmayer, Osijek, Croatia

Manuscript received 8 August 2011, accepted 24 October 2011

Introduction

The beneficial effects of n-3 polyunsaturated fatty acids(n-3 PUFA) on human health have been extensively investi-gated and that has been recently summarized by ANDERSONand MA (2009). Such effects are evident in cardiovasculardiseases, some cancers (prostate and breast) as well as ininsulin resistance.

Generally, nutritionists recommend reduction of fat con-sumption, especially saturated FA to 10% or less and in-crease of PUFA intake up to 10% of total energetic input.The ratio of n-6 PUFA linoleic acid (LA) to n-3 PUFA α-lino-lenic acid (ALA) should range from 5 : 1 to 10 : 1 (SUGANOand HIRATA, 2000), while current recommendations of then-6/n-3 PUFA ratio are < 5. Furthermore, it was shown thatthe conversion of ALA to eicosapentaenoic acid (EPA) anddocosahexaenoic acid (DHA), important n-3 PUFAs in-volved in human health maintenance, was very low inhuman tissues (ANDERSON and MA, 2009). For example,The International Society for the Study of Fatty Acids andLipids (ISSFAL) based on the results of BRENNA et al.(2009) claim that the conversion of ALA to DHA is around1% in infants, while in adults this process is considerablyreduced. Therefore, it is suggested that human diet shouldcontain not only ALA (whose direct beneficial effects onhuman health are still doubtful) but also EPA and DHA insufficient amount, especially in fast growing and develop-ing organisms (CARLIER et al., 1991).

Worldwide, poultry meat is an important source of pro-teins and lipids in human nutrition. In birds, tissues lipidcomposition can be significantly influenced by dietary lipids.Shifts in favor of PUFA increase can be achieved in tissuesof domestic feeding fowl with a high proportion of dietaryadded PUFA (STEVENS, 2004). Consequently, attempts arecarried out to rear chickens having meat FA compositionthat meets the specific demands of human nutrition. Theaddition of fish oil (rich in EPA and DHA) to broiler feedresults in a rise of these n-3 PUFAs in meat, but also impairsits organoleptic qualities resulting in “fishy” taste (RYMERand GIVENS, 2005). Therefore, researchers are performingexperiments by adding different vegetable oils to poultryfeed in order to increase n-3 PUFA in muscle tissues andchange its FA composition. In our present research, the

Arch.Geflügelk. 4/2012

same concentration of four different plant oils (sunflower– SO, soybean – SB, rapeseed – RO and linseed – LO) wereadded to standard broilers diet in an attempt to enrich n-3PUFA proportion, and lower n-6/n-3 PUFA ratio in twomuscle types (breast, BM and thigh, TM).*

It is well known that the elevated PUFA concentration inmuscles can lead to increased susceptibility to lipid (CORTINASet al., 2005) and protein oxidation. Although a limiteddegree of oxidation contributes to the typical flavor ofmeat (KANNER, 1994), oxidative processes in meat are gen-erally considered as negative, leading to undesirable meatquality changes of its technological traits (pH, water hold-ing capacity – WHC, texture, susceptibility to oxidation),appearance (colour, shape and size) and sensory attributes(odour, tenderness, juiciness, total taste, oily aftertaste,flavour) as well as to reduced storage stability (CAVANIet al., 2009; BARROETA, 2007). Despite the fact that poormeat quality characteristics are often the consequence ofincreased lipid and protein oxidation, chemical analysisthat encompass measuring of these undesirable oxidationproducts are not performed frequently. Among them, themain focus has been directed to lipid, and much rarely toprotein oxidation products (LUND et al., 2011). Proteinchanges resulting from oxidation include protein fragmen-tation or aggregation, formation of amino acid derivativesas well as changes in protein solubility and hydrophobicity,affecting the functional properties of proteins (DAVIES andGOLDBERG, 1987; STADTMAN, 1990). Oxidative modificationsof the aminoacid side chains and changes of myofibrillarnative structure through peptide scission and formation ofcrosslinks result in loss of gelling and emulsifying ability aswell as loss of WHC. The consequences are low yield incooked meats, altered quality traits and decreased juici-ness. Moreover, protein oxidation may increase proteinhardness through mechanisms including calpains, influ-encing in this way meat sensory properties. Finally, meatnutritional value is spoiled by loss of essential aminoacidsand impaired meat protein digestibility due to less sensi-tive proteolysis (LUND et al., 2011, ESTÉVEZ, 2011).

Therefore, the main objective of our experiment was toquantify the lipid (thiobarbituric acid reactive substances –TBARS) and protein (carbonyl proteins – CP) oxidationproducts in muscles of broilers fed with four different plantoils. In addition, the relationship between fatty acid pro-portion in diet and muscles was analyzed, as well as the

* Part of this work was presented on the Congress of the CroatianSociety of Biochemistry and Molecular Biology with InternationalParticipation, 17.–20. Sept. 2008. Osijek, Croatia

260 Kralik et al.: Fatty acids and lipid and protein oxidation products in poultry meat

correlation of muscle fatty acid proportion with musclelipid and protein oxidation products.

Materials and methods

Experimental design

The experiment was performed on 80 Ross 308 hybridmale broilers. One day old chickens (with average bodymass 40 g) were divided by random selection in 4 experi-mental groups (20 individuals per group). Broilers fromeach group were housed in 5 separate compartments(5 replication units) containing 4 individuals per each unit(pen). Starting temperature was 32°C, and temperaturehas been lowered during experiment to 24°C, beeing20°C at the end. Temperature, moisture and light regimes(24 hours of light exposure) were kept in optimal rangesaccording to the manufacturer’s recommendation.

Ingredients of the experimental diets according to themanufacturers’ declaration are presented in Table 1. Fromday 1 to 21 of age broilers were fed a “starter” mixturecontaining 24.8% crude protein and 12.64 ME, MJ/kg(Table 2). From 22 to 42 day of age, to the standard feed(finisher) plant oils were added to reach final concen-tration of 50 g/kg (Table 1). The applied plant oils weresunflower, soybean, rapeseed and linseed oil (treatmentgroups SFO, SBO, RSO and LNO, respectively). Sunflower,soybean and rapeseed oil were purchased in the oil factory“Čepin”, Croatia, while linseed oil was the product of“Bolio Kereskedelmi es Szolgaltato KFt.”, Boly, Hungary.The chemical composition of the experimental diets dif-fered only in the added oil sources and therefore diets wereconsidered to be isoenergetic and isonitrogenous. All dietingredients were in agreement with manufacturer’s recom-mendation.

Five chickens from each treatment (one from each repli-cation unit) with the body weight close to the average body

Table 1. Ingredients of the experimental diets according to the Inhaltsstoffe der Versuchsrationen nach Angabe des Herstellers (g

Ingredient Starter Finisher

All groups SFO

Maize (75 g/kg) 346.1 484.5

Soybean cake (46 g/kg CP) 245.8 144.8

Extruded soybean 232.4 236.8

Sunflower cake (30 g/kg) 76.8 30.0

Sunflower oil (%) 50.0 50.0

Soybean oil (%)

Rapeseed oil (%)

Linseed oil (%)

Alfalfa (17%) – 15.0

Limestone 17.4 13.3

Monocalcium phosphate 18.3 15.1

Livestock salt 3.0 3.0

L-Lysine Hcl 1.9 0.4

DL-Methionine 3.3 2.1

Premix* 5.0 5.0

* Premix (1 kg) contains: Vitamin A 3,000,000 IU; Vitamin D3 400,000 IVitamin B2 1200 mg; Vitamin B6 400 mg; Vitamin B12 3 mg; Vitamin CFolic acid 100 mg; Choline chloride 100,000 mg; Cobalt 30 mg; IodineIron 7000 mg; Zinc 10,000 mg; Antioxidant 20.000 mg; Methionine 10

weight of the group were selected at the end of experimentfor tissues chemical analysis.

The FA proportion in the diets (expressed as % of totalFA) is presented in Table 2. One of the most outstandingconsequences of plant oil addition to broiler feeds was amuch higher proportion (22.4%) of ALA in the LNO groupcompared to the other groups (3.92% in the SFO, 5.26% inthe SBO and 6.44% in the RSO). Higher n-6 PUFA contentin the SFO and SBO groups (56.9% and 54.9%), comparedto RSO and LNO groups (41.1% and 35.8%) was also de-tected. Hence, the most favorable ratio of dietary n-6/n-3PUFA was found in the LNO group, containing linseed oil.This ratio assumed the following values in final broilersdiet: 14.5, 10.4, 6.38 and 1.60 for the SFO, SBO, RSO andLNO group, respectively.

Tissue processing

At 42 day of age, birds were weighed, slaughtered by ex-sanguination and defeathered. Carcasses were manuallyeviscerated, washed and cut. After cooling, breast (M. pec-toralis major) and upper leg (thigh) muscles (M. interme-dius) were dissected without skin (BM and TM). All visibleexternal fat, including connective tissue and tendons wasremoved from sample muscles. The samples were frozen inliquid nitrogen and stored at –80°C.

Chemical and biochemical analysis

The analysis of total fat content, total fatty acids content(FA), TBARS and CP were performed for 5 individual birdsof each experimental treatment. For each bird, 4 samplesof either breast or thigh muscle were taken and subjectedto analytical procedure. Mean value of these 4 measure-ments represent experimental data for one individual bird.

Total fat content was determined by the Stoldt method(Hungarian Standard No 6830-66). 2.5 g of the samplewas boiled gently over a hot plate in 3M HCl for one hour.


manufacturers’ declaration (g/kg)./kg)

SBO RSO LNO

484.5 484.5 484.5

144.8 144.8 144.8

236.8 236.8 236.8

30.0 30.0 30.0

50.0

50.0

50.0

15.0 15.0 15.0

13.3 13.3 13.3

15.1 15.1 15.1

3.0 3.0 3.0

0.4 0.4 0.4

2.1 2.1 2.1

5.0 5.0 5.0

U; Vitamin E 6000 mg; Vitamin K3 400 mg; Vitamin B1 200 mg; 3000 mg; Niacin 8000 mg; Biotin 20 mg; Pantotenic acid 2400 mg; 150 mg; Selenium 30 mg; Copper 800 mg; Manganese 16,000 mg; 0,000 mg; Plant-mineral carrier up to 1 kg.

Kralik et al.: Fatty acids and lipid and protein oxidation products in poultry meat 261

After cooling, the material was filtered, and the residuewas washed in cold water until a neutral filtrate wasobtained. The residue was placed on a watch glass anddried for 1.5 h in an oven at 100 ± 3°C. The filter papercontaining the dry residue was placed in an extractorand the total fat content was determined by the Soxhletmethod.

From the homogenized sample, 2–4 g was taken for fattyacid analysis. Fatty acids were extracted with n-heptane,and dry sodium sulphate was added to eliminate watercontent. To the heptane solution containing fat, sodiummethylate was added and the mixture was heated at 60°Cfor 60 min. with intermittent shaking. After the addition ofn-heptane and water, the mixture was homogenized andthe heptane phase was dried by sodium sulphate. Anamount of 0.5–2.0 μg of the sample was injected into thecolumn of the Chrompack CP-9000 chromatograph withflame ionisation detector, using quartz capillary colon(300 × 25 mm) and Cp-Sil-88 as humid phase. Injectortemperature was 220°C and carrier gas was helium at235 kPa. Individual fatty acids were expressed as percent-age of total fatty acids content.

For analysis of lipid and protein oxidation products,samples were defrosted to room temperature and homog-enized in buffer solution on ice with an Ultra Turax IKAT10 homogenizer (30 seconds at high speed).

Lipid peroxidation was approximated by using a thio-barbituric acid reactive substances assay as described byRICE-EVANS and BURDON (1993). This method involves thereaction of a degradation product of lipid peroxidation,malondialdehyde and similar aldehydes, with thiobarbi-turic acid (TBA) under conditions of high temperature andacidity. The generated resulting colored adduct was meas-ured spectrophotometrically at 532 nm. The results areexpressed as milligrams of lipid peroxidation products(malondialdehyde and similar aldehydes, MDA) per kg oftissue (mgMDA/kgtissue).

Carbonyl proteins were detected by reaction with 2,4-di-nitrophenylhydrazine. The 2,4-dinitrophenylhydrazonesproduced were analyzed spectrophotometrically at 375 nmand expressed as μmol C = O/mg prot, where subscript C = Odenotes carbonyl groups (REZNICK and PACKER, 1994; DALLE-DONNE et al., 2003).

Table 2. Calculated composition of the experimental dietsKalkulierte Nährstoffgehalte der Versuchsrationen

Calculated ingredients supplied per kg of diet

Starter Finisher

Crude protein 24.8 20.0

Fat 11.4 12.0

Crude fiber 5.00 4.22

Ash 5.74 4.93

Arginine 1.66 1.27

Lysine 1.44 1.05

Methionine 0.710 0.520

Tryptophan 0.310 0.250

Calcium 1.05 0.850

Available phosphate 0.500 0.420

Na 0.160 0.160

Linoleic acid 8.30 7.22

ME, MJ/kg 12.64 13.50


Statistical analysis

Statistical analysis was done using Statistica for Windowsv.7.1. (StatSoft Inc 2005). Two-Way Anova analysis wasperformed to ascertain the impact of both dietary addedplant oils and muscle type on quantitatively determinedfatty acids, TBARS and CP of broilers in four experimentalgroups. The quantitative data obtained were presented bymean values and standard deviations ( ± SD). Followinganalysis of variance, comparison of mean values was per-formed using the Fisher’s LSD-test, at the level of signifi-cance of 5%, 1% and 0.1%. The association between therelevant parameters (FA in diet with FA in muscles, as wellas FA in muscles with TBARS and CP in muscles) was test-ed by calculation of Pearson’s correlation coefficient (r).

Results

Total fat content did not differ between experimentalgroups in either muscle type, but differed highly significantbetween BM and TM in each experimental group (Figure 1).The TM/BM fat content ratio was 2.66, 2.76, 3.05 and 2.98for SFO, SBO, RSO and LNO group, respectively. The pro-portion of fatty acids in total lipids was high, ranging from95.37% to 95.55% in BM and 95.32 to 96.36% in TM (datanot presented). There was no difference of total fatty acidsproportion in total lipid content either between experi-mental groups or between two muscle types, while total FAcontent differed significantly between TM and BM, withTM/BM ratios resembling those for total lipid content(data not presented).

The proportion of SFA, MUFA and PUFA in BM and TMof experimental groups are presented in Figure 2. SFA pro-portion in experimental groups displayed the order: SFO >LNO > RSO > SBO in BM and SFO > SBO > LNO > RSO in

x

Figure 1.Total fat content (g/100 g of tissue) in breast (BM) andtight (TM) muscles of broilers fed with different plant oils (SFO –sunflower oil, SBO – soybean oil, RSO – rapeseed oil and LNO –linseed oil (Asterisk denote significant difference between BMand TM in identical experimental group, *** = P < 0.001)Gesamtfettgehalt (g/100 g Gewebe) in Brust- (BM) und Schenkel-muskeln (TM) von Broilern, die mit Rationen mit unterschied-lichen Pflanzenölen (SFO – Sonnenblumenöl, SBO – Sojaöl, RSO –Rapsöl, LNO – Leinöl) gefüttert wurden (* kennzeichnet signifi-kanten Unterschied zwischen BM und TM in der derselben Ver-suchsgruppe; *** = P < 0,001)

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TOTA

L FA

T C

ON

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/100

gtis

sue)

SFO SBO RSO LNOEXPERIMENTAL GROUPS

BM TM

******

*** ***


TM. It was higher in BM, what was statistically confirmedfor SFO and RSO (P < 0.001) and for LNO group (P < 0.05).MUFA proportion was highest in RSO, followed in BM bySBO, LNO and SFO, and in TM by LNO, SBO and SFOgroup. Despite slightly higher proportion of MUFA in TM,this difference was confirmed only for SFO group (P < 0.05).n-6 PUFA proportion in BM was highest in SBO, followedby SFO, RSO and LNO group (no difference existed betweenthe last two groups). In TM, n-6 PUFA proportion wasequal in SFO and SBO, and lower in RSO and LNO groups.Difference between BM and TM was proven for SFO andRSO (P < 0.01) as well as for LNO group (P < 0.05). Finally,n-3 PUFA proportion was much higher in LNO compared toother groups in both muscle types. No difference in n-3PUFA proportion was recorded between BM and TM ineither experimental group.

A detailed analysis of n-3 PUFAs proportion in BM andTM of experimental groups is presented in Figure 3. Theproportion of dominant n-3 PUFA, α-linolenic acid (ALA),was much higher in LNO compared to other groups; theirorder according ALA content was LNO > RSO > SBO > SFO.ALA proportions were also higher in TM compared to BM,what was statistically proven for SFO and RSO group, butnot for LNO (due to high standard deviation). Other n-3PUFAs proportions followed the order: docosapentaenoicacid (DPA) > docosahexaenoic acid (DHA) > eicosapentae-noic acid (EPA), with highest values in LNO group. Indi-vidual n-3 PUFAs proportion did not differ between SFO,SBO and RSO groups. Some differences between BM andTM were also found: for EPA in SBO (P < 0.01) and LNO

Figure 2. Proportion of main fatty acid groups (SFA – saturated, Min experimental groups (SFO – sunflower oil, SBO – soybean oil, R(BM – breast and TM – thigh) of broilers (% of total FA, mean ± SDbetween experimental groups in the same muscle type (P < 0.05)identical experimental group; * P < 0.05, ** P < 0.01, *** P < 0.001Gehalte an den Hauptfettsäuregruppen (SFA – gesättigte Fettsäurensättigte Fettsäuren) in den Versuchsgruppen (SFO – Sonnenblumen(BM – Brust, TM – Schenkel) der Broiler (% der Gesamtfettsäuren, Mittzeichnen signifikante Unterschiede zwischen den Versuchsgruppen Unterschied zwischen BM und TM in der derselben Versuchsgruppe;

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FATT

Y A

CID

S (%

)

SFO SBO RSO LNO SFO SBO RSO LNOSFA MUFA

Main fatty acids in BM an

a a c a b

b c

b b b c b b b a a b b

***

***

*

*

group (P < 0.05), for DPA in SFO and RSO group (P < 0.01),and for DHA in SFO (P < 0.01), SBO (P < 0.01) and LNO(P < 0.05) group, with higher values recorded in BM.

Consequently, n-6/n-3 PUFA ratio was highest in SFO,followed by SBO, RSO and LNO groups in both muscletypes (Figure 4), the difference being statistically proven(P < 0.05). It seemed that the n-6/n-3 PUFA ratio is slightlyhigher in TM compared to BM, what was statisticallyshown for SFO (P < 0.05) and SBO (P < 0.01) group.

The extent of n-3 PUFAs proportion increase in LNOgroup compared to other experimental groups in bothmuscle types is calculated in Table 4. The highest increasedisplayed EPA (642% in BM and 358% in TM), followed byALA (435% in BM and 318% in TM) when compared toSFO group. Total n-3 PUFAs proportion in LNO groupincreased at most when compared to SFO group (294% inBM and 263% in TM), while n-6/n-3 PUFA ratio in LNOgroup decreased 77.6% in BM and 77.3% in TM when com-pared to SFO group.

The results of lipid and protein oxidation product deter-mination are presented in Figure 5.

Both TBARS and CP values displayed similar trend, withfollowing order of experimental groups: LNO > SFO >RSO > SBO. For TBARS differences between all experimen-tal groups were statistically significant in BM (P < 0.05). InTM no difference was recorded between SFO and LNOgroups, which differed significantly from SBO and RSOgroups; SBO and RSO groups differed as well (P < 0.05).For CP no difference could be proven in BM, while in TMmuch higher CP content was recorded in LNO group,

UFA – monounsaturated, PUFA – polyunsaturated fatty acids)SO – rapeseed oil and LNO – linseed oil) and two muscle types of five samples; different letters indicate significant difference; asterisk denotes significant difference between BM and TM in)

, MUFA – einfach ungesättigte Fettsäuren, PUFA – mehrfach unge-öl, SBO – Sojaöl, RSO – Rapsöl, LNO – Leinöl) und in den Muskelnelwert ± SD aus 5 Stichproben; unterschiedliche Buchstaben kenn-innerhalb des Muskeltyps (P < 0,05); * kennzeichnet signifikanten* = P < 0,05, ** = P < 0,01, *** = P < 0,001)

1

BM TM

SFO SBO RSO LNO SFO SBO RSO LNOn-6 PUFA n-3 PUFA

d TM of experimental groups

b a a a c b c b

c d b c b b a a

*

**

**



which differed significantly from SBO and RSO group.Furthermore, no difference was shown between SFO, SBOand RSO group in TM for CP content.

Independent of diet, TBARS and CP values were higherin TM compared to BM. The BM/TM ratio for TBARSvalues were 3.76, 4.22, 2.38 and 3.09 and for CP values1.84, 1.84, 1.47 and 3.05 in SFO, SBO, RSO and LNOgroups, respectively. These differences were not statisti-cally proven only for CP values in SBO and RSO groups.

In Table 5 the relationship between the proportion ofbasic FA groups and individual n-3 PUFAs in diet andmuscles of experimental groups is presented. SFA and n-6PUFA in diet correlated positively with n-6 PUFA (P < 0.05)and n-6/n-3 PUFA ratio (P < 0.001), but negatively withn-3 PUFA (P < 0.05). MUFA in diet correlated positivelywith muscle MUFA (P < 0.001). Dietary n-3 PUFA corre-lated positively with muscle total n-3 PUFA (P < 0.001),individual n-3 PUFAs (P < 0.001 for ALA, EPA and DPA andP < 0.01 for DHA) and negatively with n-6/n-3 PUFA ratio(P < 0.001). Finally, a high positive correlation was foundbetween n-6/n-3 ratio in diet and muscles (P < 0.001),while this ratio in diet correlated negatively with mostmuscle n-3 PUFAs (P < 0.01 for total n-3 PUFA, ALA andEPA, P < 0.05 for DPA).

The relationship between FA proportions and TBARSand CP values in BM and TM of broilers is presented in

Figure 3. Proportion of individual n-3 PUFAs (ALA – α-linolenic, EPhexaenoic acid) in experimental groups (SFO – sunflower oil, SBOtwo muscle types (BM – breast and TM – thigh) of broilers (% ofsignificant difference between experimental groups in the samebetween BM and TM in identical experimental group; * P < 0.05, *Anteile verschiedener n-3 PUFAs (ALA – α-Linolensäure, EPA – Eicosasäure) in den Versuchsgruppen (SFO – Sonnenblumenöl, SBO – SojaTM – Schenkel) der Broiler (% der Gesamtfettsäuren, Mittelwert ± Ssignifikante Unterschiede zwischen den Versuchsgruppen innerhalschied zwischen BM und TM in der derselben Versuchsgruppe; * = P <

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7

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n-3

FATT

Y A

CID

S (%

)

b b b b c c b b b b b b

a a a a

**

***

** *

SFO SBO RSO LNO SFO SBO RSO LNO

ALA EPAn-3 PUFAs in BM and T


Table 6. A highly significant positive correlation of TBARSin BM with total n-3 PUFA, ALA, EPA and DPA (P < 0.001)and DHA (P < 0.01) proportion was shown. In BM, no cor-relation of CP with FA proportions was detected, while inTM only a slight positive correlation of TBARS with EPAproportion was found (P < 0.05). On the contrary, negativecorrelation existed between TBARS value in TM and MUFAproportion (P < 0.01). Unlike in BM, in TM a significantpositive correlation between CP and n-3 PUFA (P < 0.01),ALA (P < 0.01), EPA (P < 0.001), DPA (P < 0.05), and DHA(P < 0,001) proportion was evidenced. CP in TM displayedalso negative correlation with n-6 PUFA (P < 0.01) pro-portion and n-6/n-3 PUFA ratio (P < 0.05). Finally, nocorrelation was found between TBARS and CP either in BMor in TM.

Discussion

The influence of dietary plant oils on FA profile in musclesof broilers has been investigated in numerous papers. Un-fortunately, none of these studies used identical experimen-tal conditions as ours (broiler sort, feed composition, oilscombination applied, quantity of added oils, time of treat-ment etc.) what limits the possible comparisons. NEWMANet al. (2002), studying the avian metabolism, in experi-

A – eicosapentaenoic, DPA – docosapentaenoic, DHA – docosa- – soybean oil, RSO – rapeseed oil and LNO – linseed oil) and

total FA, mean ± SD of five samples; different letters indicate muscle type (P < 0.05); asterisk denote significant difference* P < 0.01, *** P < 0.001)

pentaensäure, DPA – Docosapentaensäure, DHA – Docosahexaen-öl, RSO – Rapsöl, LNO – Leinöl) und in den Muskeln (BM – Brust,D aus 5 Stichproben; unterschiedliche Buchstaben kennzeichnenb des Muskeltyps (P < 0,05); * kennzeichnet signifikanten Unter-

0,05, ** = P < 0,01, *** = P < 0,001)

1

BM TM

b b b b b b b b aa b b b b b a

** ** ** **

*

SFO SBO RSO LNO SFO RSO LNO

DPA DHAM of experimental groups

SBO


ment using 80 g/kg dietary added sunflower oil (SO),found lower SFA and n-3 PUFA and higher MUFA and n-6PUFA in BM then we detected. AZMAN et al. (2005) added60 g/kg SO to broiler' feed what resulted in higher SFA andlower n-6 PUFA proportion in BM and TM compared to ourresults. MUFA proportion was higher in BM and lower inTM, and n-6/n-3 PUFA ratio in BM higher compared toours. Furthermore, SALAMAT DOUST NOBAR et al. (2007)detected considerably higher total SFA and MUFA as wellas lower n-6 and n-3 PUFA proportions compared to ourresults for BM and TM in research with broilers receiving20 and 40 g/kg RO from 5th to 8th week of fattening.KORELESKI and ŚWIĄTKIEWICZ also used RO (in the same con-centration as we did – 50 g/kg), what resulted in lowerSFA, MUFA and n-6/n-3 PUFA ratio, and higher n-6 andn-3 PUFA proportion. LÓPEZ-FERRER et al. (1999), using82 g/kg of dietary added RO or LO achieved in both BMand TM, lower SFA and n-6 PUFA proportion as well asn-6/n-3 PUFA ratio (for LO treatment the value was under1), and higher MUFA and n-3 PUFA proportion comparedto our results. In another study, LÓPEZ-FERRER et al. (2001)used only LO in concentrations of either 20 g/kg or40 g/kg of broiler' diet. SFA and MUFA proportions in TMof both treatments were higher, while n-6 PUFA proportionand n-6/n-3 PUFA ratio were lower compared to ours.However, n-3 PUFA for 20 g/kg LO treatment displayedlower, and for 40 g/kg LO treatment higher proportion inTM in comparison with the results we obtained. VALAVAN etal. (2006) applied 30 g/kg of either RO or LO in broilers

Figure 4. n-6/n-3 PUFA ratio in experimental groups (SFO –sunflower oil, SBO – soybean oil, RSO – rapeseed oil and LNO –linseed oil) and two muscle types (BM – breast and TM – thigh)of broilers (mean ± SD of five samples; different letters indicatesignificant difference between experimental groups in thesame muscle type (P < 0.05); asterisk denote significant differ-ence between BM and TM in identical experimental group;* P < 0.05, ** P < 0.01).n-6/n-3-Verhältnis in den Versuchsgruppen (SFO – Sonnen-blumenöl, SBO – Sojaöl, RSO – Rapsöl, LNO – Leinöl) und in denMuskeln (BM – Brust, TM – Schenkel) der Broiler (% der Gesamt-fettsäuren, Mittelwert ± SD aus 5 Stichproben; unterschiedlicheBuchstaben kennzeichnen signifikante Unterschiede zwischenden Versuchsgruppen innerhalb des Muskeltyps (P < 0,05); * kenn-zeichnet signifikanten Unterschied zwischen BM und TM in derderselben Versuchsgruppe; * = P < 0,05, ** = P < 0,01)

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**

*
feed what resulted in lower n-6 PUFA proportion andn-6/n-3 PUFA ratio in BM and TM compared to ours;nevertheless, n-3 PUFA proportion in this study was higherfor the group receiving RO, and lower in the group receiv-ing LO in both muscle types. Finally, SCHNEIDEROVÁ et al.(2007), investigating influence of two different linseed oils(with mutual inverse proportion of dominant n-6 and n-3PUFAs), used the same quantity of dietary added LO as wein our study (50 g/kg). SFA proportion of both LOs appliedwere much alike ours, while MUFA proportion in citedstudy was higher in both muscle types and for both oiltypes compared to ours. First oil type (LO1) induced low,and second (LO2) high n-6 PUFA proportion in both muscletypes, while n-3 PUFA proportion followed completelyopposite trend. Resulting n-6/n-3 PUFA ratios were verylow for LO1 (lower than ours), and considerably high forLO2 (much higher than ours) in both muscle types.
There is no doubt that dietary added plant oils in ourexperiment increased PUFA content in both muscle types.Moreover, the increased ALA levels in BM and TM providedthe necessary substrate for the synthesis of long-chain n-3PUFAs (EPA, DPA and DHA), which were not present in anybroiler’s diet. As anticipated, this process was the mostintensive in the LNO group, where the quantity of detectedlong-chain fatty acids was the highest for DPA followed byDHA, and the smallest for EPA. The highest proportions ofn-3 PUFAs, but also the lowest proportion of n-6 PUFAs inLNO group contributed simultaneously to the lowest n-6/n-3 PUFA ratio in both muscle types.

Of particular interest is the finding that in all experi-mental groups ALA proportions were higher in TM, whileEPA, DPA and DHA proportions were higher in BM. Thefinal outcome of this distribution is that no differencecould be shown between BM and TM for n-3 PUFA propor-tion in any experimental group. Our findings are in accord-ance with the fact that EPA and DHA are more prevalent inthe phospholipids fraction, and lipids in BM are rich inphospholipids (LESKANICH and NOBLE, 1997; RYMER andGIVENS, 2005). Despite of that, dark meat (TM), as well asskin, are the richest sources of all n-3 PUFAs, containinghigher proportion of lipid content (RYMER and GIVENS,2005). We also found much higher total lipid content inTM of all experimental groups, with similar TM/BM ratioranging from 2.66 to 3.05.

The results obtained by correlation analysis also confirmthat the dietary treatment with different plant oils appliedin our experiment influenced significantly the fatty acidprofile in broilers’ muscles. The most outstanding is a highlysignificant positive linear correlation for n-3 PUFA in diet(containing only ALA, see Table 3) with all n-3 PUFAs inmuscles. RYMER and GIVENS (2005) reported that the corre-lation of dietary ALA and ALA in skinless BM was poor inturkeys and broilers, while it was stronger for dark meatand much stronger for both muscle tissues containing skin.Only a very weak correlation of dietary ALA and muscletissue EPA proportion has been reported so far (LÓPEZ-FERRER et al., 2001; OZPINAR et al., 2003), while there are nodata about such a relationship with DPA and DHA. Ourresults undoubtedly demonstrate that in broilers, increasedALA content in diet does not only causes ALA rise inmuscles, but also enables the synthesis of longer chain n-3PUFAs, namely EPA, DPA and DHA, not present in broiler’sdiet.

Poultry meat is notably sensitive to lipid oxidation be-cause of its naturally high proportion of PUFA (BOTSOGLOUet al., 2002). The addition of PUFA to the poultry dietfurther enhances the possibility of both lipid and proteinoxidation. The oxidized lipids and proteins arise prior todetectable meat quality changes induced by oxidation pro-



cesses, what encourages their measurement in the purposeof meat quality validation.

Values of TBARS in BM that we recorded are comparablewith those reported by KANG et al. (2001) in the study onlaying hens fed with added palm oil diet, while our valuesin TM are higher. CHERIAN et al., 2002, in a study in whichbroilers were fed different cultivars of sorghum, andCORTINAS et al., 2005, investigating the influence of dietaryPUFA on chicken dark meat quality, found TBARS valuesthat were similar to those reported in our study.

We could not find any relevant data about CP values inbroilers meat. In a recent review dealing with feeding andprotein oxidation of meat constituents RAES et al. (2009)also claim that there are no literature data on CP values ofbroiler’ meat. Therefore we can only compare CP valuesbetween our experimental groups, i.e. the influence ofdifferent dietary treatments on generation of carbonylproteins. The highest CP values were recorded in LNOgroup, followed by SFO, SBO and RSO.

Our results of lipid and protein oxidation product meas-urement also showed that oxidation process was muchmore expressed in TM compared to BM, the differencebeing higher and more significant for lipid oxidationproducts. The larger quantity of oxidation products in TMwas expected, due to a much higher total lipid and fattyacids content in TM (Figure 1). TM, compared to BM, areparticularly vulnerable because of their higher fat propor-tion (JENSEN et al., 1998), but also the more intensiveoxidative metabolism due to better blood supply. It is wellknown that myoglobin and other heme compounds pre-sent in higher concentration in red meats, function asprooxidants in muscle tissue (Love 1983) inducing lipidoxidation (ANDREO et al., 2003; LEE et al., 2003). Protein

Figure 5. Lipid (TBARS) and protein (CP) oxidation products in bredietary added plant oils (SFO – sunflower oil, SBO – soybean oilsamples; different letters indicate significant difference betweasterisk denote significant difference between BM and TM in idenLipid (TBARS) und Protein (CP) Oxidationsprodukte im Brust- (BM) udenen Pflanzenölen (SFO – Sonnenblumenöl, SBO – Sojaöl, RSO – schiedliche Buchstaben kennzeichnen signifikante Unterschiede zw* kennzeichnet signifikanten Unterschied zwischen BM und TM inP < 0,001)

0,0

1,0

2,0

3,0

4,0

5,0

6,0m

g M

DA

/ kg

tiss

ueTBARS

***

BM

***

***

SFO SBO LNO

***

E X P E R I M E

b d c a a b c a

RSO


cross-linking recorded in red meat was associated withoccurrence of lipid oxidation products (TIRONI et al., 2002).

The TM/BM ratio of TBARS values that we measured arein accordance with the above theoretical presumptions,ranging from 2.36 to 4.22, and corresponding to theTM/BM ratio for total lipid content. However, TM/BMratio of CP was high (3.05) only in LNO group, andamounted 1.84, 1.84 and 1.47 in SFO, SBO and RSOgroup, respectively. That means that CP values measuredin our study were lower than it could be expected on thebasis of total lipid content in the same samples.

Finally, we must discuss the results of correlation analy-sis of muscle fatty acid proportion with lipid and proteinoxidation products. It is clearly evident that BM and TMextremely differ in that sense (Table 6). In BM, n-3 PUFAproportion highly significantly (P < 0.001) correlated withTBARS, while no correlation was found with CP values. Onthe other hand, in TM, high correlation was shownbetween CP and n-3 PUFA proportion (P < 0.001), whileonly a weak correlation was shown between TBARS andEPA proportion (P < 0.05).

Of particular interest is the finding of negative correla-tion between MUFA and TBARS in TM, between n-6 PUFAand TBARS in BM, as well as between n-6 PUFA and CP inTM. In TM this resulted also with negative correlationbetween n-6/n-3 PUFA and CP. It seems that the positionand geometry of double bonds in these fatty acids are lesssusceptible to oxidative changes and oxidative damagecompared to n-3 PUFA.

There are different theories dealing with the interactionof lipids and proteins in the process of their oxidation. PARKet al. (2006) reported that lipid and protein oxidation maybe related in certain oxidizing systems (i.e. hydroxyl radi-

ast (BM) and thigh (TM) muscles of broilers fed with different, RSO – rapeseed oil and LNO – linseed oil; mean ± SD of fiveen experimental groups in the same muscle type (P < 0.05);tical experimental group; * P < 0.05, ** P < 0.01, *** P < 0.001)

nd Schenkelmuskel (TM) von Broilern bei Fütterung mit verschie-Rapsöl, LNO – Leinöl; Mittelwert ± SD aus 5 Stichproben; unter-ischen den Versuchsgruppen innerhalb des Muskeltyps (P < 0,05); der derselben Versuchsgruppe; * = P < 0,05, ** = P < 0,01, *** =

μmol

C =

O /

mg

prot

.

TM

CP **

*

SFO SBO RSO LNON T A L G R O U P S

a b b b a a a a a

0,0

1,0

2,0

3,0

4,0

5,0

6,0



Table 3. Fatty acid proportion of the experimental diets (SFO – sunflower oil, SBO – soybean oil, RSO – rapeseed oil, LNO – linseedoil, % of total fatty acids)Fettsäuremuster der Versuchsrationen (SFO – Sonnenblumenöl, SBO – Sojaöl, RSO – Rapsöl, LNO – Leinöl; in % der Gesamtfettsäuren)

Fatty acids day0–21

day 22–42

SFO SBO RSO LNO

Myristic C14:0 0.100 0.100 0.090 0.100 0.040

Palmitic C16:0 12.4 12.2 12.1 10.8 10.3

Heptadecanoic C17:0 0.110 0.080 0.090 0.080 0.070

Stearic C18:0 3.72 3.43 3.53 2.92 3.61

Arachidic C20:0 b b b 0.87 0.54

Behenic C22:0 0.390 0.350 b 0.300 0.210

Tricosanoic C23:0 0.04 b b b b

Lignoceric C24:0 0.150 0.140 0.160 0.130 0.110

Miristoleic C14:1 0.020 b 0.030 0.030 b

Palmitoleic C16:1 0.100 0.050 0.090 0.120 0.090

Heptadecenoic C17:1 0.070 0.100 0.090 0.140 0.170

Oleic C18:1n9c 23.21 20.44 21.91 35.22 24.95

Eicosanoic C20:1 0.230 0.140 0.160 0.540 0.290

Linoleic 18:2n6 51.56 56.90 54.82 41.10 35.64

γ-Linolenic 18:3n6 0.040 b b b 0.100

Eicosadienoic 20:2n6 0.050 b b b b

Eicosatrienoic 20:3n6 0.030 0.040 0.060 b 0.060

α-linolenic 18:3n–3 6.220 3.920 5.260 6.440 22.380

Docosapentaenoic 22:5n3 0.060 b b b b

Docosahexaenoic 22:6n3 0.070 b b b b

Others 1.46 2.11 1.58 1.25 1.47

Σ SFAa 16.89 16.30 16.00 15.17 14.85

Σ MUFAa 23.63 20.73 22.28 36.05 25.50

Σ n-6 PUFAa 51.68 56.94 54.88 41.10 35.80

Σ n-3 PUFAa 6.35 3.92 5.26 6.44 22.38

n-6/n-3 PUFA 8.14 14.53 10.44 6.38 1.60

a SFA = saturated fatty acids; MUFA = monounsaturated fatty acids; PUFA = polyunsaturated fatty acids.b under detection limit.

Table 4. Increase of n-3 PUFA fatty acids proportion and decrease of n-6/n-3 PUFA ratio in LNO group compared to other experi-mental groups (SFO, SBO and RSO) in breast (BM) and thigh muscles (TM) of broilers (%; the highest increases are indicated byasterisk)Zunahme des Gehaltes an n-3 PUFA und Abnahme des n-6/n-3-Verhältnisses in der Leingruppe (LNO) im Vergleich zu den anderenVersuchsgruppen (SFO, SBO, RSO) im Brust- (BM) und im Schenkelmuskel (TM) der Broiler (%; die höchsten Zunahmen sind mit* gekennzeichnet)

Fatty Acids Experimental Groups

SFO SBO RSO

BM TM BM TM BM TM

α-linolenic acid 435* 318* 193 196 167 154

Eicosapentaenoic acid 642* 358* 287 293 305 223

Docosapentaenoic acid 237 229 184 185 184 143

Docosahexaenoic acid 93,1 89,2 108 115 105 73

n-3 PUFA 294 263 180 188 166 144

n-6/n-3 PUFA 77.6 77.3 72.8 72.1 63.8 60.1

PUFA = polyunsaturated fatty acids; BM = breast muscle; TM = thigh muscle


cal – generating system), but not in others (metmyoglobin– oxidizing system). Hence, muscle type in which lipid andprotein oxidation occur has a major influence on the“coupling” of the two oxidative processes. Despite the factthat the oxidative modifications of muscle proteins cantake place in the absence of lipids (i.e. metal-catalyzedreactions), it is highly unlikely that the oxidation oflipids and proteins takes independently. Lipid oxidation isthought to promote the oxidative damage of proteinsthrough the prooxidant activity of primary (hydroperox-ides) and secondary (aldehydes, ketones) lipid oxidationproducts (GARDNER, 1979; KIKUGAWA et al., 1999). Thereare numerous reports showing that lipid oxidation di-rectly promotes protein oxidation, but also those provingthat proteins are minimally affected by lipid peroxidation(SAIGAS et al., 2003). It was suggested that unexpected lowprotein oxidation may be the consequence of inherentanti-oxidant properties of proteins, which can also act asredox-active compounds, protecting themselves and otherfood components from oxidative reactions (LUND et al.,2011).

Our presented results encourage us to conclude that thebiochemical mechanisms of tissue damage by oxygen reac-tive species, resulting in lipid and protein oxidation, are ingreat extent different in broilers white (BM) compared todark (TM) meat. Detected TM/BM ratio of TBARS valuesresemble or are even higher than TM/BM ratio of total fatcontent (3.76, 4.22, 2.38, and 3.09 for TBARS versus 2.66,2.76, 3.05 and 2.98 for total fats), while TM/BM ratio ofCP values in three experimental groups are much lower(1.84, 1.84 and 1.47 for SFO, SBO and RSO, respectively).If protein oxidation resulted directly from lipid oxidation,high detected TBARS values in TM should result in higherCP values than recorded. Correlation analysis support suchspeculations, because in BM, high positive correlation was

Table 5. Relationship between fatty acid proportion in diet andmuscles (pooled data for both muscle types) of broilers at theage of 42 days (P-values for calculated correlation coefficients(r) between compared fatty acids)Beziehung zwischen dem Fettsäuremuster in der Ration und imMuskel (gepoolte Daten für beide Muskeln) von Broilern am42. Lebenstag (P-Werte für die berechneten Korrelationen (r) zwi-schen den verglichenen Fettsäuren)

Fatty acids in muscles

Fatty acids in diet

SFA MUFA n-6 PUFA n-3 PUFA n-6/n-3

SFA NS NS NS NS NS

MUFA NS 0.001 NS NS NS

n-6 PUFA 0.05 NS 0.05 NS NS

n-3 PUFA 0.05* NS 0.05* 0.001 0.01*

ALA 0.05* NS 0.05* 0.001 0.01*

EPA 0.05* NS 0.05* 0.001 0.01*

DPA 0.05* NS 0.05* 0.001 0.05*

DHA NS NS NS 0.01 NS

n-6/n-3 PUFA 0.001 NS 0.001 0.01* 0.001

SFA = saturated fatty acids; MUFA = monounsaturated fatty acids; PUFA = polyunsaturated fatty acids, ALA = α-linolenic acid; EPA = eicosapentaenoic acid; DPA = docosapentaenoic acid; DHA = docosahexaenoic acid.NS = not significant; * = negative correlation


shown for n-3 PUFA and TBARS while, on the contrary, inTM high correlation existed between n-3 PUFA and CP.

It seems also most likely that in the same muscle tissueoxidation of lipids and proteins takes place independently,at least partially. Our presumption is that in TM proteinoxidation is not provoked only by products of lipid oxida-tion. Our conclusion is supported by the finding that nocorrelation can be shown between TBARS and CP values ineither muscle type.

Conclusions

• Meat of broilers fed with dietary added linseed oil(50 g/kg) have the best muscle tissue fatty acid profile(the highest proportion of total n-3 PUFA, specificallyALA, EPA, DPA, DHA), as well as lowest n-6/n-3 PUFAratio, favorable for human diet.

• TBARS and CP values in TM (representing dark meat)were higher compared to BM (representing white meat).Our TBARS values are also higher than those reportedin literature. We presume that this is the consequence ofincreased PUFA proportion in TM, resulting from die-tary treatment.

• Lipid and protein oxidation induced by elevated PUFAproportion in muscle tissues of broilers may have differ-ent and independent mechanisms of induction andpropagation, and this process depends on muscle type.There is no correlation between TBARS and CP valuesin any muscle type.

Table 6. Relationship between muscle fatty acid proportion andTBARS and CP values in breast and thigh muscles as well as thecorrelation between TBARS and CP values in the same muscletype of broilers at the age of 42 days (P-values for calculatedcorrelation coefficients (r) between compared parameters)Beziehung zwischen dem Fettsäuremuster, den Gehalten anTBARS sowie CP in Brust- und Schenkelmuskeln sowie Korrela-tionen zwischen den TABRS- und CP-Gehalten in den gleichenMuskeln von Broilern am 42. Lebenstag (P-Werte für die berech-neten Korrelationen (r) zwischen den verglichenen Fettsäuren)

Fatty acids Breast muscle Thigh muscle

TBARS CP TBARS CP

SFA NS NS NS NS

MUFA NS NS 0.01* NS

n-6 PUFA 0.001* NS NS 0.01*

n-3 PUFA 0.001 NS NS 0.01

ALA 0.001 NS NS 0.01

EPA 0.001 NS 0.05 0.001

DPA 0.001 NS NS 0.05

DHA 0.01 NS NS 0.001

n-6/n-3 PUFA NS NS NS 0.05*

TBARS : CP NS NS

SFA = saturated fatty acids; MUFA = monounsaturated fatty acids; PUFA = polyunsaturated fatty acids; ALA = α-linolenic acid; EPA = eicosapentaenoic acid; DPA = docosapentaenoic acid; DHA = docosahexaenoic acid; TBARS = lipid oxidation products; CP = protein oxidation products.NS = not significant; * = negative correlation


Summary

In an attempt to improve the nutritional value of broilers’meat by enhancing its unsaturated fatty acid proportion,plant oils were added to the diet from 22 to 42 days of agein concentration of 50 g/kg and four experimental groupswere defined (sunflower – SFO, soybean – SBO, rapeseed– RSO and linseed – LNO). In homogenates of breast (BM)and thigh (TM) muscle tissue total fat, total fatty acids andproportion of individual fatty acids as well as lipid (thio-barbituric acid reactive substances, TBARS) and protein(carbonyl proteins, CP) oxidation products were deter-mined. A high positive linear correlation was found be-tween corresponding fatty acids in the diet and muscle tis-sue. The greatest increase of n-3 PUFAs was found in LNOcompared to other groups (P < 0.05), the same as the low-est n-6/n-3 ratio (P < 0.05). The highest TBARS and CPvalues were recorded for SBO and LNO groups in bothmuscle types. The levels of TBARS and CP determined inTM were higher compared to BM (P < 0.001 and 0.05, re-spectively). In BM a high positive linear correlation wasfound between TBARS and all n-3 PUFAs (P < 0.001), butno correlation between CP and PUFAs. In TM a high linearcorrelation existed between CP and all n-3 PUFAs(P < 0.01), but only a slight correlation between TBARSand EPA (P < 0.05). No correlation was shown betweenTBARS and CP values in either muscle types. We conclud-ed that the meat of broilers fed with linseed oil achievedthe best muscle tissue FA profile favorable for human diet,but at the same time the highest proportion of lipid andprotein oxidation products, particularly in TM. Moreover,our results indicate that the biochemical mechanism of tis-sue damage by increased meat PUFA proportion is differ-ent for white and dark meat. It also seems possible that inthe same muscle tissue oxidation of lipids and proteinstakes place independently.

Key words

Broiler, nutrition, plant oils, thiobarbituric acid reactivesubstances (TBARS), carbonyl proteins (CP), fatty acids (FA)

Zusammenfassung

Fettsäuremuster und Lipid- sowie Proteinoxidations-produkte in Muskeln von Broilern, die mit Rationen mit unterschiedlichen Pflanzenölen gefüttert wurden

Zur Anreicherung von Broilerfleisch mit mehrfach unge-sättigten Fettsäuren wurden die Broiler zwischen dem 22.und 24. Lebenstag mit Futterrationen gefüttert, die unter-schiedliche Pflanzenöle enthielten (SFO – Sonnenblumen-öl, SBO – Sojaöl, RSO – Rapsöl, LNO – Leinöl). In denHomogenaten des Brust- (BM) und Schenkelfleischs (TM)wurden der Gesamtfettgehalt, der Gesamtgehalt an Fett-säuren, die Anteile der einzelnen Fettsäuren sowie derGehalt an Oxidationsprodukten in den Lipiden (Thiobarbi-tursäure reaktive Substanzen – TABRS) und im Protein(Carbonyl-Protein – CP) bestimmt. Es wurde eine engeBeziehung zwischen dem Fettsäuremuster im Futter und inden Geweben ermittelt. Die höchste Anreicherung an n-3PUFA wurde bei Fütterung von LNO erzielt (P < 0,05), wieauch das günstigste n-6/n-3-Verhältnis (P < 0,05). Diehöchsten Gehalte an TBARS und CP wurden bei beidenMuskeltypen für SBO und LNO gefunden. Im Schenkel-muskel (TM) waren die Gehalte an Oxidationsprodukten(TBARS – P < 0,001, CP – P < 0,05) generell höher als im

Brustfleisch. Im Brustmuskel lag eine hohe, positive lineareKorrelation zwischen den TBARS und dem Anteil an n-3PUFAs vor, aber nicht für CP und PUFAs. Im Gegensatzhierzu wurde im Schenkelmuskel eine hohe lineare Kor-relation zwischen CP und n-3 PUFAs (P < 0,01) und eineleichte Beziehung zwischen TBARS und EPA (P < 0,05)ermittelt. Dagegen lagen weder für den Brust- noch für denSchenkelmuskel eine Beziehung zwischen TABRS und CPvor. Es wurde der Schluss gezogen, dass zwar mit Leinöl alsFutterfettquelle das ernährungsphysiologisch günstigsteFettsäuremuster in den Muskelgeweben erzielt werdenkann, aber gleichzeitig, vor allem im Schenkelfleisch –auch die höchsten Gehalte an Lipid- und Protein-Oxida-tionsprodukten zu erwarten sind. Die Ergebnisse unter-streichen ferner, dass Unterschiede im Oxidationsgesche-hen zwischen hellem und dunklem Fleisch bestehen. DieErgebnisse deuten auch darauf hin, dass die Oxidation vonLipiden und Protein im Gewebe voneinander unabhängigablaufen.

Stichworte

Broiler, Fütterung, Pflanzenöle, Thiobarbitursäure ReaktiveSubstanzen (TABRS), Carbonylproteine, Fettsäuren

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Correspondence: Elizabeta Has-Schön, Department of Biology, University J. J.Strossmayer, Trg Lj. Gaja 6, 31000 Osijek, Croatia; E-mail: [email protected]

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