Variability growth rate of dairy breeds calves depending on colostrum quality

Successful rearing of heifers largely depends on the supply of colostrum in the initial period of postnatal ontogenesis. The need to feed colostrum for 2-3 hours after birth is explained by the establishment of passive immunity in calves, and the amount of colostrum directly correlates with the prevention of diseases. In addition, an enhanced feeding regimen with milk or milk replacer during the milk period of rearing not only affects growth, but also promotes the development of all organs and systems. Scientific research was conducted at "Turar" LLP, Fedorov district, Kostanay region, Republic of Kazakhstan. The object of the research were Holstein animals. It was found that feeding colostrum with an immunoglobulin content of more than 22% on the Brix scale contributes to an increase in immunoglobulins in the blood serum on the 3rd day after birth to 7.0 g/dl and more. This has a positive effect on the dynamics of live weight growth of heifers from the first days of life, as well as on the protein and mineral levels at the end of the milk period of rearing. Thus, heifers with the immunoglobulin in serum level of 7.0 g/dl and higher reliably outperformed their peers with the immunoglobulin in serum level of 5.0 g/dl in live weight gain by 5.1-6.7% and in relative growth rate by 4%. As a result of the data obtained during the study, it can be concluded that the higher the immunoglobulin level in colostrum, the more immunoglobulins are transferred to newborn calves, which contributes to high protection against potentially pathogenic microflora and maintaining a high immune status of young animals, as well as high rates of live weight gain. Thus, the average daily gain over the period was 703 g for the first group and 753 g for the heifers of the second group, with a difference of 50 g (P<0.01).