Young cattle genotype influence on protein and feed energy bioconversion into protein and energy of the carcass edible part

The aim of the study is to assess the efficiency of transformation of nutrients and energy of the feed ration by purebred bulls (group I) and castrate gobies (group III) of the black-and-white breed and its crosses with Holstein ½ Holstein × ½ black-and-white (group II, group IV - bulls-castrates) into meat products. Research objectives: to establish the consumption of crude protein and energy per 1 kg of live weight gain, the mass of protein and extractable fat in the edible part of the carcass, the yield of protein, extractable fat and energy per 1 kg of pre-slaughter live weight, to determine the value of the bioconversion coefficient of protein and feed energy in the food protein and energy of carcass pulp in young animals in LLC "Kolos" in the Orenburg Region. It was found that purebred bulls of the I group and purebred castrate bulls of the black-and-white breed of the III group differed in a more significant consumption of crude protein and energy per 1 kg of live weight gain than hybrid peers ½ Holstein × ½ black-and-white groups II and IV by 8,66-13.05 and 1.29-3.70 %, respectively. At the same time, purebred young animals of groups I and III were inferior to hybrid peers of groups II and IV in terms of the weight of edible parts of the carcass by 7.23-9.13 %, the protein content in the pulp of the carcass - by 5.27-6.77 kg (13.83-16.23 %), but exceeded them in the mass of extracted fat by 1.11-1.59 kg (3.21-5.39 %). It was found that the coefficient of bioconversion of the feed protein into the protein of meat products in purebred black-and-white bulls of group I and castrate bulls of the same genotype of group III was 7.98 and 7.50 %, in hybrids of groups II and IV - 8.10 and 7.82 %, the coefficient of energy bioconversion in young animals of the experimental groups was at the level of 5.94 and 6.23 %, 6.14 and 6.50 %, respectively. It is characteristic that the bulls were distinguished by a higher value of the protein bioconversion coefficient, and the castrated bulls - energy.