Activity of NAD metabolism enzymes and DNA concentration in the liver during chicken ontogenesis

: A reverse interrelation is established between the content of NAD and DNA in the chickens liver at different stages of ontogenetic development, especially pronounced at the stages of embryogenesis. The content of NAD which is the least in the liver of the 8-day embryos increases with development of chickens and reaches the maximum level by the 6-month age. The content of DNA is maximum in the embryonal period. The activity of NAD-pyrophosphorylase in the liver nuclei has the low value at early periods of the embryonal life and rises with development of organism, reaching the constant values in one-, two- and 6-month chickens. Judging by the curve of the NAD-glycohydrolase activity in the liver nuclei, the hydrolase breakdown of NAD occurs only after chickens hatching.