A relationship between amino acids composition and biological value of egg proteine and amino acids content in blood of the Lohmann White cross hens

The biosynthesis of egg proteins is integrated into a total protein metabolism. In a poultry flock of laying hens of the Lohmann white cross, a content of essential and nonessential amino acids in eggs and blood was evaluated at 26 th, 52 th and 80 th weeks of oviposition. The studied parameters were found to depend on the terms of productive use. During the oviposition, an egg weight and the yolk rate increased, whereas the egg production and the white rate, on the contrary, decreased. The amino acids content in eggs and the concentration of free amino acids in blood increased simultaneously, thus indicating an increase in protein metabolism activity until the 80 th week. During the egg-laying period, a concentration of amino acids in blood was almost constant and the level of lysine was the highest, which probably resulted form the feed additives used due to the lack of lysine in natural fodder corn. At the beginning and the end of an oviposition, the bulk egg protein is not biologically valuable as some amino acid scores are low. Identified age dynamics of these parameters can be used to assess the eggs quality and optimize the amino acid content in the laying hen diets.