Formation of meat productivity and transformation of nutrients and feed energy into carcass pulp of bulls of various breeds.

The results of meat productivity and conversion of nutrients and feed energy in bulls of the Schwyz, Simmental, Aberdeen Angus, Kazakh white-headed and Belgian blue breeds when aged from 8 to 17 months are presented. During this period, they consumed an average of 3235 kg of dry matter, 261.5 kg of protein and 25722 MJ of metabolic energy from the feed from self-feeders and had an average daily increase of 1328-1565 g with an advantage of 145-237 g per day in favor of the Belgians (P>99). In terms of pre-slaughter live weight of 658 kg, they exceeded their peers by 66-101 kg, in terms of carcass weight by 98-130 kg and in terms of pulp content by 90-116 kg, but in terms of raw fat weight, they were inferior by 8.7-10.6 kg. The first place in terms of weight and yield of internal and fat carcasses, and the second in terms of bone, cartilage and tendons (17.9%) and slaughter yield (61.86%) is occupied by Aberdeen Angus bulls. Belgian animals showed the highest transformation of dry matter, protein, and MJ of feed exchange energy per 1 kg of absolute gain, pre-slaughter live weight, and carcass pulp. Gobies of the Shvitskaya and Kazakh white-headed breeds transformed the dry parts of the feed into pre-slaughter live weight by 6.2-17.9%, and into the fleshy parts of the carcass by 10.2-46.6% lower than their peers of the breeding groups. They also showed a similar pattern in the transformation of protein and metabolic energy of the feed into an absolute increase (5.8-18.0%) and carcass weight (10.5-42.4%). An intermediate position in these indicators is occupied by Aberdeen-Angus peers, whose conversion rate of dry matter per 1 kg of carcass pulp was 11.83 kg, which is 32.9% more than that of Belgian and 10.5% less than that of Swiss gobies. In terms of protein conversion, Aberdeen Angus bulls outperformed Belgians by 16.4 per 1 kg of pre-slaughter live weight, 32.2 per 1 kg of carcass weight, and 31.9% in carcass pulp. At the same time, they were inferior in these indicators to the Swiss bulls, respectively - by 9.4, 1.4 and 9.5%.