Effect of dietary conjugated linoleic acid on egg yolk fatty acid profile in laying hens

Abstract

The aim of this study was to examine the possibility of conjugated linoleic acid (CLA) depositing and fatty acid profile changing in egg yolks of laying hens fed with CLA during four weeks of experiment. 40 laying hens were randomly divided into two groups, control group fed with feed mixture of standard chemical composition for laying hens and experimental group fed with the same feed with added 2% CLA. Fatty acid composition of 12 egg yolks from each group were analysed at the beginning and 28th day of the experiment by gas chromatography. At the beginning of experiment there were not any changes at saturated, monounsaturated and polyunsaturated fatty acid composition and conjugated linoleic acid was not detected. After 28 days of experiment, the content of saturated fatty acids was significantly higher in experimental group (59.83%), compared to the control group (33.16%), while the content of monounsaturated fatty acids were significantly lower in experimental (22.61%) than in control group (53.36%) (P<0.01). The content of polyunsaturated fatty acids at 28th day of experiment were from 12.25% (control) to 17.38% (experimental group) (P<0.01). Also, as expected, CLA was not detected at 28th day in the control group, while in the experimental group was 4.28%. Feed intake wasn't influenced by added CLA. This study showed that dietary modifications could lead to nutritionally favorable changes in the fatty acid composition of egg yolks that are products for human consumption.

Cilj ovog rada bio je da se ispitaju mogućnosti deponovanja konjugovane linolne kiseline (CLA) i promene masnokiselinskog profila u žumancetu jaja koka nosilja hranjenih sa dodatkom CLA tokom četiri nedelje eksperimenta. 40 koka nosilja podjednako je podeljeno u dve grupe, gde je kontrolna grupa hranjena potpunom krmnom smešom za ishranu koka nosilja, a ogledna grupa je dobijala istu hranu uz dodatak 2% CLA. Analize masnokiselinskog sastava, po 12 žumanceta svake grupe, vršene su nultog i 28. dana gasnom hromatografijom. Na početku eksperimenta (nultog dana) u obe grupe nisu uočene značajne promene u sadržaju zasićenih, mononezasićenih i polinezasićenih masnih kiselina, dok CLA nije detektovana. Nakon 28 dana sadržaj zasićenih masnih kiselina je bio značajno viši u oglednoj (59,83%), u poređenju sa kontrolnom grupom (33,16%), dok je sadržaj mononezasićenih masnih kiselina bio značajno niži u oglednoj (22,61%) u odnosu na kontrolnu grupu (53,36%) (P<0,01). Sadržaj polinezasićenih masnih kiselina 28. dana eksperimenta se kretao od 12,25% (kontrola) do 17,38% (ogledna grupa) (P<0,01). Konjugovana linolna kiselina nije detektovana 28. dana u uzorcima žumenceta kontrolne grupe, dok je u oglednoj grupi iznosila 4,28%. Dodatak konjugovane linolne kiseline nije uticao na konzumaciju hrane. Značaj ovih rezultata je što ukazuju na to da ishranom koka nosilja možemo kontrolisati sadržaj željenih masnih kiselina u jajetu kao krajnjem proizvodu za ishranu ljudi.