The aim of this study was to determine the effect of 3 sire bulls from different genetic lines on the yield, chemical and mineral composition of milk produced by their daughters that belonged to black and variegated cattle kept in Kazakhstan, in the consecutive lactations and milking seasons. The research included 60 dairy cows, whose average share of HF breed genes did not exceed 50%. The cows were kept on a dairy farm called  Wiktorowskoye, located near Tarnov (Kazakhstan). The highest milk yield, fat and protein content were recorded for the offspring of the bull Hamlet (H-239). The lowest body weight was achieved by daughters of Hamlet (H-239) and was significantly different from the other cows at p£0.01 and p£0.05. The milk yield per body weight (bw) showed that cows in the 3rd lactation produced 911 kg of milk/100kgb.w.. Daughters of Hamlet (H-239) distinguished themselves by the best milk yield to body weight conversion rate of 985 kg/100 kgb.w.. The ratio of protein to fat was satisfying and ranged from 0.82 (1st lactation) to 0.80 (3rd lactation). Cows from the group H-239 produced milk with the highest content of fat. In the 1st lactation, it equalled 3.95%, rising to 4.02% in the 3rd lactation. Depending on the milking season, the highest fat content was in the AU (4.02%) and WI seasons (3.99%) and the lowest one occurred in the SU season (3.87%). The highest protein content was observed in cows of group M-370 and amounted to 3.29% (primiparous cows) and 3.24% (3rd lactation) as well as 3.52% (WI) and 3.46 (AU). The highest content of SSC (2,464 thousand/cm3) was found in cows of group B-361 in the WI season, with statistical differences p £0.01 and p £ 0.05. The content of FFA was the highest in daughters of the bull M-370 bull, followed by the offspring of the bull H-239.

21.3.2016