Influence of Poultry Diet on the Fatty Acid, Mineral and Vitamin Composition of the Egg: a Review

The hen’s diet influences the fatty acids, minerals and vitamins content in eggs. The vitamin A content of eggs responds slowly to dietary vitamin A changes but the change is rapid for riboflavin. Pantothenic acid, folacin, biotin, vitamin B12 and D respond greatly to dietary increases. Feed vitamin transfer efficiency to the egg is very high (60-80%) for vitamin A, high (40-50%) for riboflavin, patothenic acid, biotin and vitamin B12, medium (15-25%) for vitamins D3 and E, and low (5-10%) for vitamin K1, thiamin and folacin. Attempts have been made to reduce egg cholesterol contents by altering the yolk fatty acid composition. The cholesterol-lowering effects of polyunsaturated fatty acids (PUFA) have been recognized. Feeding layers a diet rich in PUFA resulted in a large increase in the relative and absolute concentrations of PUFA in yolk total lipid. Conjugated Linoleic Acid (CLA) have been reported to have a wide range of health-beneficial effects, including anticarcinogenic, antiatherosclerotic, antiatherogenic, anti-diabetic, immune stimulatory effects , influencing both fat metabolism and protein deposition. One way to increase the CLA content in eggs is through supplementation of the layer diet with CLA. A combined incorporation of CLA into egg yolk, together with that of PUFA, would lead to great health benefits to man. This information will be useful for the production, consumption and quality standardization of enriched eggs. The iodine and selenium content of the egg may vary depending on the hen’s diet while the iron content of eggs shows minimum variability with the hen’s dietary iron content. Laying hens fed the usual way and offered additional minerals produced eggs that were rich in phosphorous, had 2.5 times more iodine and 4 times more selenium.