Changes in breeding and genetic properties of the Sakhalin population of the Holstein breed over the period of long-term breeding

As a result of the conducted research, the breeding and genetic mechanism of the formation of productive traits in cows of the Sakhalin population has been studied. The modern breed group combines four related populations – American, Canadian, Japanese and Sakhalin. Studies have shown that a limited population limits fertility, does not show heterosis, and reduces adaptability in subsequent generations. The main breeding and genetic parameters of breeding herds have been determined. The correlation coefficient between the milk yield of cows for 305 days of the first lactation and the service period was -0,227±0,013, the coefficient of linear regression, respectively (