Lipid profile in feed and egg yolk from barn, cage, and organic systems at different hen ages

Aim of the present research was to study the relationship between feed and egg yolk lipid fractions from Hy-line Brown hens reared in different housing systems (cage, barn, organic) throughout the whole hen laying cycle. Egg yolk and feed samples were analysed at 27, 30, 35, 43, 53, and 68 weeks of hen age by measuring total lipid content (by Soxhlet) and fatty acid composition (by gas chromatography). The total lipid content of feeds was the same in all the rearing systems without variations during the production cycle. No significant variation of lipid content was observed in egg yolk. The feed administered in the organic system had higher PUFA as well as lower MUFA and SFA percentages than those of the other two systems. No clear trends during hen production cycle in all housing systems were observed for feed fatty acid profile. With regards to the fatty acid composition of egg yolk, SFA percentage was the same for all the rearing systems while organic eggs presented lower MUFA and higher PUFA values. Egg yolk fatty acids changed as a function of hen age. Significant correlations were observed between feed and egg yolk for MUFA and PUFA, but not for SFA.