The Influence of Dietary Protein and Energy Levels on the Protein and Lipid Content of the Hen’s Egg

Abstract The effect of four dietary protein and two energy levels on the gross chemical and physical composition of the egg has been investigated. It was found that increasing the dietary protein level from 12 to 18% resulted in an increase in the weight of all parts of the egg, particularly the yolk, an increase in the concentration of both yolk protein and albumen protein and a decrease in the concentration of yolk lipid. These effects were most apparent at suboptimum dietary protein levels. Increasing the dietary energy from 2086 to 2209 Cal./kg. increased the yolk weight of eggs but had little effect on the weight of the other components. The increase in the amount of yolk protein and lipid and total protein per egg associated with the increased energy level was due to an increase in egg size and not to a chemical enrichment of the egg components.