Weight growth of heifers of the dairy period from mothers of different ages

Relevance. To obtain highly productive animals, it is necessary to introduce new technologies for purposeful cultivation of repair heifers based on the general patterns of individual development by periods and phases of ontogenesis.The purpose of the work is to study the influence of the age of mothers on the growth of chicks during the dairy period. Methods. For the research, all newborn heifers were divided into groups depending on the age of their mothers: 1st group from heifers; 2nd group from cows for the second calving; 3rd group from cows for the third calving; 4th group from cows for the IV calving and senior calving. Weight gain was determined by the change in body weight from birth to 6 months of age by monthly individual weighing. Heifers were weighed immediately after birth and up to 6 months of age (monthly). Based on the results of weighing, the absolute, average daily and relative weight gain was calculated. Results. As a result of the conducted research, it was found that heifers with a lower live weight are obtained from heifers, which remains so until the end of the dairy period. She was 4.3–5.3 kg less at birth, or 11.3–13.9%, and 9.0–13.4 kg, or 3.95–6.25%, at 6 months of age. Chicks from mothers grew better after the second lactation. Their live weight was the highest. She was 227.7±2.32 kg at the age of 6 months. Considering the dynamics of changes in average daily live weight gains by months (periods) of cultivation, it should be noted that in the first two and fourth groups, there is a decrease in live weight gains in the second month, and then an increase in them in the first three groups in the third and fourth months of cultivation with a further decrease in 5 and 6 months (the first and second group). In calves from cows of III and older lactation (group III and IV), fluctuations in live weight gain are observed over the months of cultivation.