CANADIAN BULLS INFLUENCE ON GROWTH, DEVELOPMENT AND MEAT PRODUCTIVITY OF HEREFORD BULLS OF SIBERIAN BREED
The object of the study is the sons of bulls of the Hereford breed of Canadian selection (I group) and Hereford bulls of the Andrianov type (II group). The purpose of research is to study the influence of Canadian breeding bulls on the growth, development and meat productivity of Andrianov's Hereford bulls. The work was carried out in the breeding reproducer of Andrianovsky LLC, Bogradsky District of the Republic of Khakassia. When forming groups at the age of 8 months, the difference in live weight in experimental bulls was insignificant (216.3 and 216.4 kg). With intensive rearing, the live weight of bulls of group I at 15 months of age was 399.2 kg, bulls of group II - 422.8 kg, bulls of Siberian selection significantly (P≥0.99) exceeded peers of Canadian selection by 23.6 kg (5.9 %). At 18 months, the experimental animals met the requirements of the elite-record class. The average live weight of bulls of Siberian selection was 529.9 kg, Canadian selection - 506.0 kg, bulls of the Andrianov type significantly (P≥0.99) exceeded by 23.9 kg (4.7 %). According to the average daily gain from 8 to 15 months of age, the differences between the experimental bulls are 111.9 g (12.8 %) in favor of the bulls of group II (P≥0.999). The average daily gain in live weight for the entire growing period in bulls of Canadian selection was 965.7 g, Siberian selection - 1045.0 g, which is higher by 79.3 g (8.2 %) (P≥0.95). The slaughter yield in bulls of group I was 60.9 %, bulls of group II - 59.7 %, peers of Canadian selection were superior in this indicator by 1.2 %. The greater energy value of 1 kg of pulp by 112.8 kJ was characterized by the descendants of Canadian bulls - 4795.2 kJ, against 4682.4 kJ in Siberian bulls. They differed in the largest area of the "muscle eye" and the diameter of muscle fibers: by 7.25 cm<sup>2</sup> and 0.5 µm, respectively. To improve the herd in terms of meat productivity, we recommend using Canadian breeding bulls in reproduction.