The purpose of this research is to study the present data on the effect of different dosages of vitamin A (retinol acetate) on the metabolism and localization of protein substances (protein) in the body of experimental animals (fattening bull calves). The authors use the concept of conversion of protein substances (protein) from the diet feed into the main nutrients of the edible part of the carcass (cuts) of bull calves fed on diets with pulp granules. The authors evaluate the morphological parameters of the animal after slaughter. For the experiment, 45 heads of black-and-white bull calves at the age of 12-13 months with a live weight of 270-290kg were selected. They were distributed according to the principle of similarity into three experimental groups of 15 heads each. The groups differed in diet, namely, an increase in the dosage of vitamin A in the second and third groups by 25 and 30% relative to the first group. According to the slaughter data and the study of the morphological composition of carcasses, the authors found that it was necessary to introduce vitamin A preparation into such diets. In this experiment, the authors used retinol acetate with the biological activity of 1 mln international units in 1 g, so that their content in the diets was 23-24 thousand international units per 100kg of live weight (optimally derived dose, depending on the live weight of the animal during the experiment). This contributed to an increase in the average daily weight gain of bull calves by 11.7% and an increase in carcass weight by 9.2%, including flesh weight by 11.1%. In the carcass flesh, the protein content increased by 15.4%, fat by 15.2%, and energy by 8.2%. The conversion rate of protein substances (protein) of the feed into the edible protein of the flesh of the carcass increased by 1.33% and the energy of the feed by 1.2%.

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The data on the influence of different doses of vitamin A on feed conversion in the main nutrients of the edible portion of the carcass of bulls fed on diets with malt sprouts are given. It was found out that in this diet it is necessary to add A-vitamin supplements,  23-24 thousand IU per 100 kg of live weight. It improves average daily gains of bulls by 11.4 %, of the weight of the carcass – by 6.0 %, including pulp by 7.2 %. The content of protein in the flesh of the carcass increases by 7.6 %, fat – by 8.8 % energy –  by 8.2 %. Conversion ratio of feed protein to food protein increases by 1.23 %, of energy feed – by 0.77 %.