Amino Acid and Lipid Accretion and Metabolism in the Meat-Type Hen Embryos Developing in Eggs with Low and High Yolk Content

Peculiarities of amino acid and lipid accretion and metabolism during embryogenesis were studied in the meat-type hens, which are associated with different relative yolk contents (a model of conditions of embryonal development of altricial and precocial birds). Prior to the 18-day embryogenesis, intensive lipid catabolism without accumulation of macroergs was found in the group with a high yolk content, while a higher level of amino acid metabolism was typical of the group with a low lipid content at the 18th–21st days of embryogenesis. The character of egg arginine utilization by embryos indicates a possibility of synthesis of this amino acid at early stages of embryonal development. There were revealed significant differences in the glycine synthesis levels: whereas at the period between the days 0 and 17 glycine was intensively produced in the both groups, on the days 18–21 this amino acid was synthesized only in the group with the high relative yolk content. Differences in the body cystine concentration between the 17- and 21-day old embryos depended on the relative yolk content, which indicates effect of this sign on the time of onset of keratin synthesis. The obtained data indicate that the yolk composition affects essentially the direction of metabolic processes in embryos.__________Translated from Zhurnal Evolyutsionnoi Biokhimii i Fiziologii, Vol. 41, No. 2, 2005, pp. 119–124.Original Russian Text Copyright © 2005 by Zhuravlev, Dolgorukova, Salamatin, Fisinin.