Effect of Dietary Supplementation with Conjugated Linoleic Acid, with Oleic, Linoleic, or Linolenic Acid, on Egg Quality Characteristics and Fat Accumulation in the Egg Yolk

The effects of conjugated linoleic acid (CLA) with other fatty acids on the fatty acid composition of egg yolk and on egg quality characteristics were studied in 5 groups: 1) CLA 0% (control), 2) CLA 2%, 3) CLA 2% + oleic acid (OA) 2% (CLA + OA), 4) CLA 2% + linoleic acid (LA) 2% (CLA + LA), and 5) CLA 2% + α-linolenic acid (LNA) 2% (CLA + LNA). Some parameters of egg quality such as shell thickness, shell strength, yolk color, yolk index, egg diameter, and Haugh units were aggravated when CLA was fed alone, but the quality was improved when CLA was combined with some other fatty acids. The egg production rate, which was decreased by feeding CLA alone, was improved by co-supplementation with LA or OA. An increase in CLA content was observed in all the dietary groups fed CLA for 2 wk. Feeding hens with CLA + LNA led to a linear increase in CLA content in the egg yolk after the fourth week of the feeding trial. Egg yolks from hens given CLA had considerably higher amounts of saturated fatty acids and lower amounts of monounsaturated fatty acids than egg yolks from the control group. The pattern of change in CLA concentration during the feeding trial was similar to the level of C18:0, which was inversely correlated with the level of C18:1. The unsaturated fatty acid co-supplementation strategy applied in this study offers insight into the mechanism of CLA accumulation in the egg yolk without apparent adverse effects on egg quality and egg production.