Captivity diets alter egg yolk lipids of a bird of prey (the American kestrel) and of a galliforme (the red-legged partridge)

The salient feature of the fatty acid profile of kestrel eggs collected in the wild was the very high proportion of arachidonic acid (15.2% +/- 0.7% o f fatty acid mass n = 5) in the phospholipid fraction of the yolk. Kestrels in captivity fed on day-old chickens produced eggs that differed from thos e of the wild birds in a number of compositional features: the proportion o f linoleic acid was increased in all the lipid fractions; the proportion of arachidonic acid was increased in yolk phospholipid and cholesteryl ester; the proportion of alpha -linolenic acid was decreased in all lipid classes , and that of docosahexaenoic acid was decreased in phospholipid and choles teryl ester. Partridge eggs from the wild contained linoleic acid as the ma in polyunsaturate of all the yolk lipid fractions. Captive partridges maint ained on a formulated diet very rich in linoleic acid produced eggs with in creased levels of linoleic, arachidonic, and n-6 docosapentaenoic acids in the phospholipid fraction; reduced proportions of alpha -linolenic acid wer e observed in all lipid classes, and the proportion of docosahexaenoic acid was markedly reduced in the phospholipid fraction. Thus, captive breeding of both the kestrel and the partridge increases the n-6/n-3 polyunsaturate ratio of the yolk lipids.