THE STATE OF HOMEOSTASIS OF HIGHLY PRODUCTIVE DAIRY COWS OF DIFFERENT LEVELS OF GENETIC VALUE DURING THE MILKING PERIOD
The article deals with a comparative analysis of the level of milk productivity, milk quality and dynamics of blood indicators of Holstein cows during the milking period. During the milking period, the milk yield of cows in the third experimental group was highly reliable at 4001 kg of milk (P≤0,001), which is 644 kg more than in the second group and 925 kg more than in the first group. The mass fraction of fat varied from 4.08 to 4.18 %%. In the first group, the mass fraction of protein is 3.09, in 2 - 3.14 and in the third - 3.13 %%. 165 kg of milk fat (P≤0.01) was reliably obtained from animals of the third group during the period of distribution, the second experimental group - 137 and the first - 129 kg. The yield of milk protein in experimental animals of the third group is 125 kg (P≤0.001), 2-105 and 1 - 95 kg. From animals of the second group received - 105 kg and the first - 95 kg of milk fat. The content of globulin in the blood serum of group 1 cows at the beginning of milking is 56.0 g/l, at the end - 53.9 g / l, which is significantly higher than the level in other groups (P≤0.05). In group 3 cows at the end of the period, creatinine significantly increased to 74.8 mmol/l (P≤0.05). The content of alkaline phosphatase in the blood at the beginning of separation in all examined animals is normal. The level of glucose in the blood of cows in the range of 3.6 - 4.0 at the beginning and 2.7 - 4.3 at the end of the milking period (at a rate of 2.0 - 4.8 mmol/l).