Physiological and Biochemical Status of Highly Productive Dairy Cows of Different Genetic Value Level in the First Phase of Lactation
Studies on the complex improvement of milk production characteristics and functional qualities of dairy cattle allow us to reveal mechanisms of physiological regulation of animals. The work was aimed at analyzing relationship between a milk productivity level, milk composition of Holstein cows and a state of fatness and biochemical blood parameters of highly productive animals during lactation. The data of zootechnical control, milk yield for 100 days of lactation, fat and protein weight percentage (on the Bentley 150 device), milk fat and protein yield were taken into account. Fatness was assessed by a 1-5 rating scale. In serum the biochemical analyzer Chem Well (USA) identified a number of biochemical values. The experimental data were processed (Excel 2007). Reliability was assessed by Student’s t-test. Four groups of animals with different productivity were selected. The first group included productivity of 6,500-7,000 kg of milk, the second - 7,000-7,500, the third - 8,000-8,500 and the fourth - 8,500-9,000 kg. For 100 days of lactation in the third group the yield was 3,761 kg, which is by 48.2 kg more than in the fourth, and by 218.5 and 748 kg more than in the second and first groups. Fatness in the first month in the first group amounted to 3.67, in the fourth - 3.44 points (P<0.01). It amounted to 3.54-3.55 points (P<0.01) in the second and third groups. Serum protein in the first group amounted to 79.9 g/l (norm 72.0-86.0), in the fourth - exceeded 7.5 g/l (P<0.05). Cholesterol in the first, third and fourth groups reduced (norm of 4.5-6.0 mmol/l). The obtained data present the possibility of adjusting relations of physiological and genetic processes to regulate milk production of cows in the first phase of lactation. In continuation of the scientific experiment we will collect a database on health indicators for population-genetic studies in order to use indicators of the physiological status of animals in dairy cattle selection.