Population-genetic parameters of dairy productivity traits of cows of Ukrainian Red-and-White and Black-and-White dairy breeds

The study population-genetic parameters of milk productivity traits was carried out on the cows stock of Ukrainian Red-and-White and Black-and-White dairy breeds. The heritability, correlation variability and repeatability of milk yield, fat content and total milk fat yield were investigated. The coefficients of heritability traits that characterize dairy productivity of cows, differed in some variability depending on the estimated lactation and breed, but in all cases were reliable under different degrees of Fisher's criterion. Milk yield, milk fat content and total milk fat yield were almost equally determined by the genotype of animals with little difference within lactations. The values of milk yield heritability coefficients for accounted lactation of cows of Ukrainian Red-and-White dairy breed LLC "Mlynivsky Complex" showed that this indicator was depending on hereditary factors by 21.5-28.5 percent and 71.5-78.5% - from paratypical, respectively. In the herd of breeding Ukrainian Black-and-White dairy breed in the breeding plant PE "Burynske" the heritability coefficients of milk yield were slightly lower (h2 = 0.184-0.224). The fat content of milk was different in comparison with milk yield value by significantly higher heritability coefficients regardless of lactation and breed with variability in 0,341-0,405. The correlation between milk yield and fat content in cow's milk of Ukrainian Red-and-White dairy breed LLC "Mlynivsky Complex" was within -0.081… -0.192, and Black-and-White dairy breed of breeding plant PE "Burynske" within recorded lactations – 0.107 ... -0.183. High enough and reliable coefficients of milk yield and milk fat heritability between the first and second lactations in the herd of "Mlynivsky Complex" LLC (0.433 and 0.455) and PE Burynske (0.391 and 0.505) indicated to the possibility of efficient selection of cows by these important productive traits for the first lactation.