Influence of protein concentration, amino acid supplementation, and daily time to access to high- or low-protein diets on egg weight and components in laying hens.

Feeding a 13% CP diet based on corn and soybean meal and supplemented with methionine to laying hens results in reduced egg weight in comparison with hens fed a corn and soybean meal methionine-supplemented diet containing 16% CP. An experiment was conducted to determine whether the egg weight reduction could be eliminated by supplementing the low-protein diet with additional lysine, methionine, and tryptophan or by adding glycine and glutamic acid to increase the amino nitrogen to a level equivalent to 16% CP. The influence of the dietary treatments on the weight of the major egg components was also determined. In a second experiment, the influence of time of day of feeding the 13 or 16% CP diets on egg weight and egg components was determined. Adding additional amino nitrogen in the form of glycine and glutamic acid or increasing the levels of lysine, methionine, or tryptophan individually or in combination failed to prevent the depression in egg weight of hens fed the lower protein diet. Measurement of egg components demonstrated that the reduction in egg weight was primarily associated with a reduction in albumen content of the egg. Feeding a high-protein diet from 1400 to 0800 h and a low-protein diet from 0800 to 1400 h resulted in egg weight equivalent to that from hens continuously fed the high-protein diet. The lower weight of the albumen in eggs from hens fed a 13% CP diet may be due to a lower availability of amino acids for protein synthesis during the 3- to 4-h period when the ovum is in the magnum.