Denys G. Age features of skeletal muscles proteins and amino acids metabolism in different breeds of fattening cattle

Object - age and breed characteristics of proteins synthesis and breakdown in skeletal muscle of meat cattle bred in western region of Ukraine. Purpose - determine age and breed characteristics of proteins synthesis, breakdown and metabolism of specific amino acids labeled with radioactive carbon in skeletal muscle and protein metabolism indices in cattle blood of different breeds (Volyn meat, Simmental and Ukrainian black spotted dairy breed and its crosses with Aberdeen-Angus), which were grown for meat. The methods: biochemical (spectrophotometric, chromatographic), radiological, bioengineering, statistics. Novelty: age-related features of protein and lipid synthesis and lysine phenylalanine and histidine metabolism in skeletal muscle of different breed calves (Volyn meat, Simmental, Ukrainian black spotted dairy breeds and crosses with Aberdeen-Angus) were studied for the first time. The analysis of lysine, histidine and phenylalanine utilization in the synthesis of proteins, lipids and energy processes in skeletal muscle of bull-calves of various breeds all ages was accomplished in vitro. It was shown that lysine is mainly used in the synthesis of proteins (> 80%). The synthesis of protein and lysine is more intensive in skeletal muscles of meat breeds bull-calves and crosses in comparison with dairy breeds. 36 to 45% phenylalanine is used in the synthesis of proteins; the rest is subjected to catabolism. Phenylalanine is used less in protein synthesis in skeletal muscles of meat breed bull-calves and crosses in comparison with dairy breeds. The use of histidine in the synthesis of proteins, lipids and energy processes in skeletal muscle depends on the animals’ age and genotype. Its utilization in the synthesis of protein makes 35-55%, and in the synthesis of lipids - 12.6%. The dynamics of protein and lipid synthesis in skeletal muscles of different breeds of 3 - to 18-month old calves was established. It was revealed that age-related changes of protein content in skeletal muscle of bull-calves doesn’t always correlate with the intensity of their synthesis. The influence of splitting degree of the diet protein on cattle growth intensity at fattening was established. Results:new data on age features of proteins synthesis and radioactive carbon labeled lysine, phenylalanine and histidine metabolism in bulls’ skeletal muscles of Volyn’ meat, Simmental, Ukrainian black-and-white dairy breeds and cross-breed of the last with Aberdine-angus. It have been shown that the intensity of protein synthesis in skeletal muscle of all studied bull breeds were decreasing and the intensity of their oxidation and use in the lipids synthesis were increasing during 3 to 18 months of life. Synthesis and breakdown of proteins in skeletal muscles of meat breeds and their crosses were more intensively than in the bull of dairy breeds. The level of nonessential amino acids in the quadriceps muscle protein of dairy breeds bulls were increasing with age, while in the meat breeds found to increasing level of essential amino acids. The contents of free amino acids and urea in blood plasma were significantly higher in bulls of dairy breeds. The blood plasma and skeletal muscle of all bull breeds with age had increased aminotransferases activity, because of higher catabolism of amino acids. The increase of gains and skeletal muscles proteins synthesis when rumen-undegradable protein content in bulls diet was increased have been pointed.