The genetic productivity potential of Holstein heifers of different selections in conditions of the Volgograd region

The article presents results of a comparative assessment of intensity, dynamics of growth and development of Holstein heifers of two ecological-genetic types considering the factor of the age. Experimental studies were conducted in the conditions of a dairy unit for milk production, "Donskoe" farm enterprise, LLC, Surovikinsky district, the Volgograd region. Despite the fact that at birth the Dutch heifers were superior to the Russian ones with respect to the live weight by 4.0 kg, by the third month of age the live weight of the heifers in both groups was equal and amounted to 102.4 and 102.5 kg, respectively. Under the same feeding and keeping conditions, the heifers in Group I were established to surpass the heifers in Group II in terms of the overall live weight gain by 1.3 and 0.7 kg at 3 and 10 months of age, respectively. The heifers in Group I had higher average daily live weight gain than heifers in Group II by 5.5% (P ≥ 0.999) at the age of 3 months and by 4.5% (P ≥ 0.999) at the age of 10 months. The intensive rearing procedure enabled reaching the heifers' live weight, corresponding to the minimum breed requirements for insemination, i.e. 365.5 kg in Group I and 366.3 kg in Group II by the age of 15 months. Thus, that heifers of Russian selection had good growth and development indices in all life periods in the arid zone of the Volgograd region.