The ability to maintain productive qualities with age in holstein cows

Any successful decision in animal husbandry largely depends on the timely analysis of a huge number of signs and information. It was found that the productivity of 663 first heifers was high and amounted to 9159 kg. The mass fraction of fat is not high (3.91 %) and protein in the milk of the first heifers contained 3.44 %. Modern Holstein dairy cattle are characterized not only by an abundance of milk, but also by a high fat content of more than 4.2 %. Here we observe a one-sided selection for the amount of milk. This is confirmed by the milk yield of cows during the second lactation – 10 571 kg, while the animals retain and to some extent increase the fat content in their milk by 3.96 %. The amount of milk fat and protein will increase by 417 kg and 363 kg, respectively. The increase in the growth of dairy products is significant (p>0.999). According to all the laws of milk production (and these measures exist on the farm), we observe a significant increase in milk yield for the 3rd lactation by 1493 kg, 10652 kg, versus 9159 kg when compared with the first lactation (p>0.999). During the fourth, fifth and sixth lactation, productivity increases compared to the first and second lactation, the highest milk yield was obtained in cows at 6 lactation of 11 490 kg. With regard to the mass fraction of fat and protein, it should be noted that cows retain the ability to have the mass fraction of fat and protein that was determined by origin. And it does not decrease with increasing milk yield. Qualitative changes in milk have not been identified. The mass fraction of fat in milk ranged from 3.91 to 3.96 %, similarly, the content of the mass fraction of protein remains in milk with an increase in milk yield. When calculating the repeatability coefficient, we observe consistently high values, so the milk yield coefficient between the first and second lactation was r =0.89, between the second and third r = 0.97, between the third and fourth r= 0.96, between the fifth and sixth r= 0.94.