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EFFECT OF DIFFERENT OILS SUPPLEMENTED TO LAYING HENS' DIETS ON THE QUALITY OF EGGS AND THE FATTY ACIDS CONTENT IN EGG YOLK
Gordana Kralik
; Poljoprivredni fakultet Svučilišta u Osijeku, Osijek, Hrvatska
Zoran Škrtić
; Poljoprivredni fakultet Svučilišta u Osijeku, Osijek, Hrvatska
Zlata Gajčević
; Poljoprivredni fakultet Svučilišta u Osijeku, Osijek, Hrvatska
Danica Hanžek
; Poljoprivredni fakultet Svučilišta u Osijeku, Osijek, Hrvatska
Sažetak
The research was carried out on 90 laying hens of the Hy-Line hybrid. Hens, being 32 weeks old, were divided into three groups and fed commercial diets containing 17% of crude protein and 11.60 MJ ME. The research lasted for 28 days. The control group (C) was given diets supplemented with soybean oil in the amount of 5%, and experimental groups (E1 and E2) were fed diets that contained a combination of fish oil and rapeseed oil supplemented in different amounts. Diet of the E1 group contained 3.5% of fish oil and 1.5% of rapeseed oil, and the E2 group had 1.5% of fish oil and 3.5% of rapeseed oil. During the experiment, laying hens were monitored for their production traits: live weight at the beginning and end of experiment (g), food consumption (g), and laying intensity (%). The quality of produced eggs (n=17 per each group) was assessed on the 28th experiment day (fresh eggs), and 14th day after storing eggs at 4 °C. The following were assessed: egg weight, albumen and yolk weight, egg shell weight and thickness, shell firmness, shape index, albumen height, pH of albumen, yolk color and HU (Haugh units). Products of lipid peroxidation (TBARS), presented in mMxg-1 of a sample, were determined on the sample of six yolks taken from each group. In order to determine the quality of eggs, the following devices were used: Eggshell Force Gauge Model-II, Egg Multi-Tester EMT-5200, electronic micrometer, the PB 1502-S scales, the MP120 pH meter and the UV/VIS JENWAY 6305 spectrophotometer. The fatty acids content of in yolk lipids was determined on 5 samples taken from each group by the Chrompack CP-9000 chromatograph equipped with flame ionization detector. Portion of eicosapentaenoic (EPA, C20:5n-3), docosahexaenoic (DHA, C22:6n-3), α-linolenoic (LNA, C18:3n-3), PUFA n-3, PUFA n-6, as well as PUFA n-6 /PUFA n-3 ratio were shown as percentages in relation to total of fatty acids content in yolk lipids. Differences among groups were determined by the t test. Data analysis was completed with the Statistica 7.1 software (StatSoft, Inc. 1984-2005). Statistically very highly significant differences (P<0.001) were determined between the C and E1 group, as well as between the C and E2 group. In hens’ end weights of the E1 and E2 groups no statistically significant differences (P>0.05) were determined. In both periods of egg quality assessment (fresh eggs and eggs stored for 14 days at 4°C) no statistically significant differences (P>0.05) were determined for egg weight, yolk color, albumen height, shape index, HU and portions of albumen, yolk and shell. Statistically significant differences (P<0.05) in both assessment periods were determined for shell firmness and thickness and for albumen pH values. Values of lipid peroxidation measured in yolks of fresh and 14-day stored eggs were statistically very highly significant (P<0.001). Higher contents (P<0.05) of EPA, DHA, LNA and PUFA n-3 acids were observed in yolk lipids of the E1 group if compared to the control and E2 group. The PUFA n-6 content was considerably higher (P<0.05) in yolks of the control group than of the E1 and E2 groups. More favorable ratio of PUFA n-6/n-3 was determined in yolk lipids of the E1 group than of the control and E2 groups (P<0.05).
Ključne riječi
laying hens; soybean oil; rapeseed oil; fish oil; egg quality
Hrčak ID:
26514
URI
Datum izdavanja:
28.6.2007.
Posjeta: 1.616 *