Evaluation of the quality of beef obtained from young animals of different seasons of birth and slaughter based on a set of physical, chemical and nutritional indicators

The study was conducted to evaluate the influence of the season of birth and slaughter of Black-and-White bulls on meat productivity and the biochemical status of muscle tissue (amino acid, fatty acid, and elemental composition) to scientifically substantiate seasonally differentiated feeding standards. The experiment was conducted in the Orenburg region on three groups of bulls, 20 heads each: Group I autumn-born (slaughtered in March), Group II winter-born (slaughtered in July), and Group III spring-born (slaughtered in September). The rations were the same for each age year-round. Slaughter was at 18 months. Live weight at slaughter: Group I 537.3±5.43 kg, Group II 496.8±5.72 kg, and Group III 505.4±5.37 kg. The chemical composition, amino acid content (GOST 34132-2017), fatty acid content (GOST R 55483-2013), and 20 mineral elements (ICP-MS) were determined in the longissimus dorsi muscle. Group I bulls had the highest dry matter content (24.21%), fat (1.84%), energy value (4.39 MJ/kg), and protein quality index (7.2). The longissimus dorsi muscle of the animals of group II was characterised by a reduced amount of lysine (by 0.98%), methionine (by 0.23%), valine (by 0.62%), arginine (by 0.90%), histidine (by 0.27%), oleic, linoleic, linolenic and arachidonic acids, with an increased content of alanine, serine, glycine, proline and palmitic acid. The most pronounced disturbances in mineral metabolism were revealed in group II: a decrease in the amount of potassium by 13.3%, calcium by 20.1%, magnesium by 20.2%, zinc by 20.2%, selenium by 25.0% with an increase in the accumulation of lead (by 1.98 times) and arsenic (by 1.68 times). Winter and spring births are associated with decreased lipogenesis and disrupted amino acid and mineral metabolism. These young animals require seasonally adapted dietary adjustments with the addition of Zn, Se, I, Ca, K, and Mg.