Intensification of reproduction of a highly productive dairy cattle herd

The research work was carried out in a breeding facility for dairy cattle breeding with a milk yield per cow of 10,564 kg and a reproduction level of 96.6 %. Semen of Holstein bulls was used for reproduction. At dry-off pregnant cows were immunized against a range of bacterial, viral and parasitic diseases. After birth, the calves were injected with vitamin E and selenium, dectomax and gradually immunized against common infections. Data on 922 heifers were included in the analysis, including 192 obtained through inseminating cows with sexed semen. Heifers were inseminated at 13–15 months of age. Fertility rate after the first insemination was 67.4 %, calving at the age of (710 ± 2) days. Early calving and balanced feeding ensured high milk yields in full lactation and standard period – on average 9401 and 8854 kg of milk with the fat mass fraction of 4.32 %, protein of 3.38 % and the number of somatic cells of 73 thousand/ml. After calving, the first insemination was carried out on average in 82.6 days, the efficiency was 61.8 %, the insemination index was 1.60, the service period averaged to 107.5 days. When using sexed semen, the fertility rate after the 1st insemination was the same – 67.7 %. The age at calving in animals of the Vis Ideal line was 20 days more compared to their peers of the R. Sovereign line (722 versus 702 days, P < 0.05). Milk yield in full lactation and its standard period were higher in animals of the R. Sovereign line – 9304 and 8890 kg versus 8753 and 8461 kg, which indicates the positive effect of early calving on animal productivity. Early calving of heifers is a necessary condition for a highly productive herd. The results of the research are recommended to be used not only at dairy farms of the Republic of Belarus, but also in other countries with developing dairy cattle breeding.