Effects of conjugated linoleic acid supplementation in layer diet on fatty acid compositions of egg yolk and layer performances.

Conjugated linoleic acid (CLA) is a mixture of positional and geometric isomers of linoleic acid with conjugated double bonds. Conjugated linoleic acids have been reported to have a wide range of health-beneficial effects, including anticarcinogenic, antiatherogenic, antidiabetic, and immune stimulatory effects. The objective of this study was to investigate the incorporation of CLA into eggs. Three hundred 27-wk-old layers were allocated to 5 dietary treatments (0, 1, 2, 3, and 4% CLA) with 5 replicates. The results of the study showed that average daily feed intakes were similar in all treatment groups, although hens fed with 4% CLA tended to consume less feed than other hens. Body weight gain and mortality rate were not significantly different (P > 0.05). Hens fed 4% dietary CLA had reduced egg, yolk, and albumen weights (P < 0.05). Yolk color significantly decreased as dietary CLA increased (P < 0.01). Shell thickness and Haugh units were not influenced by the dietary CLA. Concentrations of CLA and saturated fatty acids in egg yolk lipids increased as dietary CLA increased (P < 0.01), whereas concentrations of monounsaturated fatty acids and polyunsaturated fatty acids decreased as dietary CLA increased (P < 0.01). It can be concluded from the present experiments that increasing the amount of CLA fed to hens will increase the amount of CLA in egg yolk and that this increase is accompanied by a reduction in the amount of yolk polyunsaturated fatty acids but an increase in yolk saturated fatty acids. Egg size, yolk weight, and Roche-fan determined yolk color significantly decreased at the highest level of CLA supplementation.