[Carboxylation processes in cattle with different levels of productivity].

The experiments were conducted on bulls-analogs of the black-piebald and Simmental breed which differ from each other in the intensity of live weight gain (18-31%) as well as on lactating cows-analogs of the black-piebald breed which differ in the level of milk productivity (41-80%). The intensity of the carboxylation processes (CO2 fixation) as well as of protein and lipids biosynthesis in the liver of the bulls from a heavy-producing group (the second group) is shown to be considerably higher than in the low-producing animals (the first group). In venous blood plasm of the second group bulls the content of urea and citrate was higher (by 29-141 and 33%, respectively) than in the first group animals. Blood plasma of the lactating cows from a heavy-producing group contains more urea (57-70%), citrate (146-80%) and total protein (10-14%) than that of animals with low milk productivity. Similar regularity is also observed as to the amount of urea and citrate of milk of cows with a higher milk productivity (by 40-50 and 51-53% higher respectively, than in the low-productive animals).