The objective of the study is to evaluate the effect of acidophilic thick sour milk on the performance and biological indicators of calves. The scientific and farm trial was conducted in 2021–2022 at Bolsheurinskoye CJSC in the Kansk District of the Krasnoyarsk Region using Red-and-White calves. Two groups of 25 day-old calves with a birth weight of 39.0–42.0 kg were formed. The control group received dairy feed according to the farm's established schedule, while in the experimental group, starting from the 11th day and continuing through the 60th day, one-third of the whole milk and skim milk was replaced with acidophilus thick sour milk. Absolute growth, body measurements, and index calculations were calculated using generally accepted methods. Including acidophilic thick sour milk in the calf diet increased live weight by 5.3 kg by the end of the sixth month, with an average daily gain of 753 g, a 5.0 % increase compared to the control group. Feeding acidophilic thick sour milk during the weaning period had a positive effect on the health, growth, and development of the calves. Feed consumption was approximately the same between the groups, but the second group saved 50 kg of whole milk per calf. Feed costs per 1 centner of live weight gain decreased by 2.8 %. The young animals of the experimental group had 57.0 % fewer gastrointestinal disorders; at all ages, they outperformed their peers in live weight – at the end of the experiment, the difference was 19.1 kg (P > 0.95) with a survival rate of 96.0 %. The bulls of the experimental group had more pronounced meat forms: compact and stockily built, less high-legged and less elongated. In terms of thoracic index, compactness index, and pelvic-thoracic index, these animals were superior to their peers at 18 months by 1.0; 2.3 and 1.7 %, respectively, and in terms of elongation index, they were inferior by 1.5 %. A decrease in the cost of live weight gain in the second group by 269.2 rubles. (2.4 %) increased production profitability from 31.1 to 34.4 %.
Lefler et al. (Thu,) studied this question.