Live weight as an indicator of morphobiochemical blood composition of heifers under intensive breeding technology

Purpose: within the framework of the research work, studies were carried out on the biochemical composition of the blood serum of highly productive cows, different periods of lactation and during the dry period, with tethered and loose housing.Materials and methods. The object of the study were cows of black-and-white Holsteinized breed with a productivity of more than 8500 kg on the farm. Blood sampling for biotesting was taken from 108 cows before morning feeding. Animals of the experimental groups were formed according to different periods of lactation and during the dry period with different methods of keeping. The study was conducted on the basis of the laboratory of biochemistry and physiology of animals of the SZNIIMLPKh named after A. S. Emelyanov.Results. In the period from 1-100 days of lactation, there is an increase in calcium from physiological norms by 9.6%, calcium-phosphorus ratio by 32.6 % and phosphorus deficiency by 6.7 %. Fluctuations in the level of calcium in the blood serum from 7.89-12 mg%, phosphorus from 3.02-3.75 mg%. During the peak of lactation, a decrease in the amount of calcium by 2.7 % is noticeable, as well as a calcium-phosphorus ratio by 1.2% an increase in phosphorus by 4.6 %. Within the group, calcium and phosphorus values ranged from 7.13-13.74 mg%, 2.86-4.48 mg%, respectively. During the period of attenuation of lactation, an increase in the content of calcium by 5.3 %, calcium-phosphorus ratio by 10.8%, a slight decrease in phosphorus by 1.3 % is observed. Calcium values range from 8.23-12.32 mg%, phosphorus from 3.02-4.69 mg%. In the dry period, there is a deviation from the reference values of calcium, phosphorus, calcium-phosphorus ratio by 14.4; 6.7 and 8.4 %, re spectively. There is a difference in the level of calcium within the group from 5.82-10.64 mg%, phosphorus from 2.94-4.05 mg%. The level of calcium, calcium-phosphorus ratio in the blood serum of the examined animals in all periods of lactation on loose content are below the norm by 2.3-11.8 % and 6.7-13.6 %, respectively. In the blood of animals of all groups, calcium values range from 4.36-13.45 mg%, phosphorus from 3.06-5.24 mg%.