In the course of the research conducted at Agro-Soyuz LLC (Kabardino-Balkarian Republic, Chegemsky district), the goal was to study the productivity of 69 first-calf cows of the Gomitinsky black-andwhite breed, the daughters of three breeding bulls, depending on the forms of inheritance or the leading breeding characteristics of dairy productivity (milk yield, fat content), for the definitions of which were used by a new methodology, which is a modified version of the methodology widely used in breeding work with dairy cattle.As a result of determining the forms of inheritance of milk yield in experimental first-calf cows, it was found that the largest share among them fell on animals with milk yield due to such a form of inheritance as regression of the mother (44.9%), the smallest share – on first-calf cows with milk yield due to the dominance of the father (7.3%). When determining the forms of inheritance of fat milk, the same trend was observed as when determining the forms of inheritance of milk yield, that is, among 659 first-heifer cows, the most animals were from the mother regression group (42%), and the least were animals from the father dominance group (4,4%). The established difference between groups of first-calf cows with different forms of inheritance of the breeding trait turned out to be quite significant and reached, in some cases, 2368 kg in milk yield per lactation (p>0,999), 0,32% in fat content (p>0,99).

https://orcid.org/0000-0002-9239-8591Аннотация. В работе рассмотрены особенности роста и развития ремонтных телок, полученных в результате применения разных степеней инбридинга. Сравнение интенсивности роста инбредных телок с их аутбредными сверстницами показало превосходство инбредного молодняка над аутбредным по живой массе в возрасте 0

The article presents the results of research on the comparative assessment of the growth, development and meat productivity of calves and castrates of Kalmyk and Simmental breeds under the same conditions of feeding and maintenance and identification of ways to increase the profitability of beef production by using the physiological state of young animals. The experimental young animals received the same amount of feed by volume and the composition of the diet was the same. As a result of the conducted studies, it was found that the live weight of bulls of both breeds with their intensive cultivation exceeded the mass of castrates in all age periods. After weaning, there was no significant difference in the live weight of calves of the Kalmyk and Simmental breeds, which had a live weight of 255.6 and 253.9 kg, respectively, and by the age of 15.5 months, many bulls of both breeds reached from 500 to 520 kg. Castrates of both breeds grew less intensively. However, in the final period of fattening, they gave a high average daily increase (more than a kilogram). The Kalmyk castrati were less demanding of coarse feeds and used them better. According to the indicators of the control slaughter, it can be noted that the mass of carcasses of bulls of both breeds is the same, and castrates had such a mass of carcasses only at the age of 18 months. At the same time, the carcass mass of castrates of the Simmental breed was 7.6 kg lower than the carcass mass of Kalmyk castrates. Bulls and castrates of both breeds gave an exceptionally high slaughter yield. At the same time, animals of the Kalmyk breed have a higher slaughter yield due to the large accumulation of internal fat. An analysis of the data on the efficiency of beef production when selling one head of bulls at 15-16 months of age compared with castrates shows that the level of profitability per sold head is higher for both breeds by 1.8 and 4.3%, respectively. Thus, due to the peculiarities of the hormonal status of bulls, compared with castrates, they have an increased ability to grow, protein synthesis and reduced fat formation. However, castrates can also be grown extensively and for a longer time in less favorable conditions and receive high-quality beef, steers – only intensively and for a limited period (up to 16-18 months).

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The article studies the influence of the frequency and time of consumption of colostrum on the immunobiological reactivity of lambs obtained from mothers of the same age, selected according to the principle of analogues. It has been established that first lambers (9–16 months) with intensive rearing and abundant feeding have an average level of resistance of the organism and its indicators are characterized by stability. The offspring obtained from these first lambers (experimental group) in terms of the level of immune parameters are not inferior to their peers obtained from the ewes of the control group. Lambs from first lambers in terms of lysozyme activity of blood serum, immunoglobulin content are superior to their peers from older ewes (the difference is not statistically significant, P> 0.05). At the same time, young animals regardless of the age of their mothers have the same vitality. The lambs' mortality from birth to wean in the experimental and control groups was approximately the same - 7.2 and 8.0%, respectively.