Nitrogen, Methionine and Cystine Content of Hen’s Eggs. Their Distribution in the Egg White and Yolk

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Abstract
Chicken eggs were analyzed for the sulfur-containing amino acids and nitrogen. As the pullets aged and were fed a low-protein diet, the nitrogen quantity decreased in the egg white and increased in the egg yolk. Aging of the pullet, in itself, was not an important factor when a high-protein diet was fed, since the younger as well as the older pullets showed an increased quantity of nitrogen in both egg white and egg yolk under these conditions. Changes shown by the nitrogen values were generally paralleled by similar changes in the cystine and methionine values. The cystine/methionine ratio in the egg white decreases with the aging of the pullet, regardless of the diets employed; the ratio increases in the egg yolk as a result of aging, but it is statistically significant only during the low-protein dietary regimen. Enzymatically digested casein in the hen's feed increases the cystine and methionine content of the egg to the same extent as does casein.

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