Economic and useful traits of cows of different ages

Intensive use of highly productive animals has revealed new problems associated with reducing the duration of productive use of animals and reducing their reproductive abilities, which lead to a decrease in the number of young animals for rearing and fattening for beef. Therefore, the study of the infl uence of age on the productive traits of cows is relevant and has practical signifi cance. The purpose of the work was to evaluate cows for economically useful traits depending on the age of the animals. It has been found that the milk yield for lactation increases with age in cows. If from fi rst-calf heifers has been received 5163,8±212,3 kg of milk, then 6106,5±201,7 and 6846,8±231,7 from cows of the third and fourth lactation, respectively, this was more by 942,7 kg or 18,2 % and 1683,8 kg or 32,6 %. Milk yield increases gradually from lactation to lactation with increasing age of cows and thus confi rms the association of improving the productive traits of animals with the laws of development, i.e. the onset of their physiological maturity. It has been revealed that the farm does not have optimal conditions for the full manifestation of the genetic potential of productivity, and therefore cows of the third and fourth lactation have lower milk yields than possible. So, the estimated milk yield of fi rstcalf heifers to mature cows practically corresponds to the milk yield that was received from cows after IV lactation. The diff erence between groups of cows in the content of individual components of milk was insignifi cant, although there is a positive trend to reduce the content of protein and casein with increasing age of cows. Cows bred on the farm have high indicators of reproductive ability. So, they have a short period of open day from 26,6±0,61 days (II lactation) to 43,7±1,11 days (III lactation), the optimal pregnancy period and calving interval (less than a calendar year). The level of profi tability of milk production increases with increasing milk yields, which increase with age.