Features of formation of milk productivity of cows of red steppe breed

Abstract

Duration and conditions of fetus development, its live weight at birth are indicators that have not only general biological significance, but also possible breeding characters. Even more often, the need for selection of young animals is noted with an allowance for duration of embryonic development and its influence on further milk productivity and reproductive capacity. The research was carried out in LLC "Obriy" of Pokrovskyi district of the Dnipropetrovsk region on heifers of red steppe breed (n = 150). Four groups of heifers are selected: with short, medium, elongated and optimal uterine development. By heifers were determined the growth and development indicators, productivity, reproductive capacity. Economic monitoring had been carried out by us relative to expediency of using the heifers of the under-investigation groups by counting the amount of additional products received. It was established, that in 72.7% of heifers the duration of uterine development was 280-290 days. Accordingly, 19.3% and 8.0% of heifers had short and prolonged uterine development. In the main growing periods, the largest live weight had heifers with the period of uterine development of 290 days or more. However, on average daily gains of live weight, the advantage was on the side of individuals, in which the period of uterine development was 286-290 days. Thus, this indicator in heifers of ІІ-ІV groups from birth to 6 months of age was 656.7-684 g, which is more by 3.1-7.5% than those with the period of uterine development of 279 days or less. A similar trend was observed during growing periods of 6-12 and 12-18 months. Compared to heifers of Group I, the advantage was 10.9-13.8% and 2.7-7.0%, respectively. In the 24-monthold age, the best gains were in individuals of ІІ-ІV groups: 468.9-480.5 g, while in the age group І the experimental group, this indicator was 401.1 g. The research have shown that live weight determines the age of the first insemination of heifers. The live weight of the repair heifers of the experimental groups for the first insemination ranged from 363.8 to 398.5 kg in the group, that is 75-80% of live weight of the full-age cow, which is the best indicator for reproduction of the herd. So the heifers of ІІ-ІV experimental groups were inseminated at 71.0-46.9 days earlier, that is, at the age of 548.3-572.4 days, compared to the analogues of the first experimental group. In the individuals of ІІ-ІV groups, the first calves were obtained at the age of 819.4-840.1 days. The advantage for live weight of the individuals of these experimental groups was retained for the first calving: from 467.2 to 519.6 kg. It should be noted that here and the output of calves for 100 cows is more by 0,4-6,3% compared to the first heifers of the first group. The results of milk productivity studies show that animals of the first experimental group in the first lactation by 2.8% lagged behind the standard breed with milk yield of 2818.4 kg. In the second and third lactation, an increase in the lagging behind the breed standard by 3....