YOLK LIPIDS AND THEIR FATTY-ACIDS IN THE WILD AND CAPTIVE OSTRICH (STRUTHIO-CAMELUS)

A comparative study has been made of the major lipid fractions and the ir fatty acid compositions in the yolk of eggs from ostriches under wi ld and farmed conditions. There were no differences in the lipid conte nts and proportions of the lipid fractions between the two groups of y olks. In both groups of yolks triacylglycerol and phospholipid were th e major fractions. In the eggs from the wild ostriches, all the lipid fractions displayed substantial concentrations of C18 polyunsaturated fatty acids, triacylglycerol being particularly rich in linolenic acid and phospholipid rich in linoleic acid; phospholipid displayed substa ntial concentrations also of C20 and C22 polyunsaturates. There were c onsiderable differences in the fatty acid compositions between the yol ks. Those from the farmed birds displayed lower proportions of C18 pol yunsaturates, particularly linolenic acid, throughout the lipid fracti ons. Compensatory increases were displayed most obviously in the conce ntrations of oleic acid and palmitoleic acid as well as other acids. T he distinctive and extensive changes in fatty acid composition, partic ularly relating to the polyunsaturates, are discussed with respect to overall dietary requirements and specificities for embryo metabolism a nd possible effects on reproductive performance.