The impact of reproductive capacity indicators of simmental cattle on their milk productivity

It is well known with an increase of milk productivity of cows their reproductive capacity in general became worse. Therefore, it is important to establish optimal parameters of the first age insemination and first calving, duration of service- and inter-calving periods. In view of the above, the purpose of our researches was to study the influence of reproductive capacity parameters of Simmental cows on the formation of milk productivity. The study were conducted on 331 cows in agricultural LLC «Litynskyy» Drohobych raion, Lviv oblast. Evaluation of milk productivity and reproductive capacity of the animals (in 20 years) were performed according to the data of zootechnical accounting for the first, second, third and the best lactations. The differences in rates of milk productivity depending on the parameters of their reproductive capacity were established. Animals with age of first fruitful insemination 18.1–20.0, with first calving age – 27.1–29.0, duration of service period – 101–120 and duration of the inter-calving period – 381–400 days had the best yields and the highest quantity of milk fat. According to the above mentioned indicators of milk productivity they are likely dominated by animals with bigger or smaller indicators of reproductive capacity, but in most cases, this advantage was unreliable. It was found positive highly significant links between indicators of reproductive capacity of cows and milk yield. The highest correlation coefficients were observed between age of first calving and their milk yields, depending on lactation, they were 0.380–0.498, lower – between age of first insemination and milk yield – 0.316–0.456 and the lowest – between service- and inter-calving periods and yield – 0.124–0.335; 0.127–0.331 respectively. The impact of the abovementioned indicators on yield was within 23.13–39.88; 28.63–45.02; 30.98–35.17%, respectively.