Authors: RAHİM AYDIN
Abstract: Dietary conjugated linoleic acid (CLA) decreases the ratio of unsaturated fatty acids/saturated fatty acids (UFA/SFA) in yolk and induces embryo mortality in fertile chicken eggs. The objective of this study was to determine if oils rich in UFA would prevent CLA-induced changes in the yolk fatty acid composition and embryo mortality in the fertile eggs. Each diet supplemented with 0.5% corn oil (Group A), 0.5% CLA (Group B), 0.5% CLA plus 10% canola oil (Group C), 0.5% CLA plus 10% olive oil (Group D) or 0.5% CLA plus 10% corn oil (Group E) was fed to 12 laying hens per treatment. Hens were artificially inseminated weekly. Eggs were collected and incubated daily. Three eggs from each group were obtained for fatty acid analysis. After 6 days, Group B had 100% embryo mortality, whereas overall embryo mortality (%) in groups A, C, D and E was 5%, 7%, 4%, and 3%, respectively. The levels of CLA (%) in the yolks from groups A, B, C, D, and E were 0.05%, 2.67%, 1.05%, 0.93%, and 1.25%, respectively. Yolks from Group B had 3.8- and 3.7-fold decreases in the ratios of 16:1(n-7)/16:0 and 18:1(n-9)/18:0, respectively. Adding canola or olive oil to the CLA diet prevented the CLA-induced increase in 16:0 and 18:0 levels and decrease in 18:1(n-9) level. As yolk from the Group B had a higher level of SFA, egg yolk from the groups C, D, and E had a lower level of SFA compared to Group A. While egg yolk from the Group D had increased level of monounsaturated fatty acids (MUFA), the egg yolk from the Group E had a decreased level of MUFA. Dietary CLA decreased the levels of MUFA and UFA significantly (P < 0.05). However, adding oils to the CLA diet (Group C, D, or E) restored the level of UFA in the egg yolk. This study shows that oils rich in UFA prevent CLA-induced embryo mortality. This study also suggests that the adverse effects of CLA may be due to an increased ratio of SFA to UFA.
Keywords: Conjugated linoleic acid, fatty acids, embryo mortality, laying hens
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