Fatty Acid Changes in Egg Yolk of Hens on a Fat-Free and a Cottonseed Oil Ration

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Abstract
Two groups of hens were placed on a rigid fat-free and a 4% cottonseed oil ration, respectively. Alternate eggs were incubated and analyzed. No difference in egg production was noted but fertility and hatchability and low mortality of embryos were favored by the fat-free ration. Analyses of the egg yolks showed no change in moisture, total fat, phospholipid or cholesterol content. Six double bond acids disappeared from the glycerides of the eggs of hens on the fat-free ration after 4 weeks and 5 double bond acids after 8 weeks. Two, three, and 4 double bond acids decreased more slowly reaching 16 to 25% of their control level in 14 weeks. The phospholipid acids showed similar changes. On the same basal fat-free ration plus 4% cottonseed oil the 6 double bond acid disappeared at the same time as on the fat-free ration, but the 3, 4, and 5 double bond acids reached a minimum after two weeks. The two double bond acid remained unchanged. It is concluded that the hen cannot synthesize polyunsaturated fatty acids from non-fat precursors, but that it can synthesize 3, 4, and 5, but not 6, double bond acids from linoleic (two double bond) acid.