Use of feed nitrogen by young pigs of meat genotypes, depending on metabolizable energy and available essential amino acids level in diet

In the system of high-grade nutrition of pigs, the completeness of compound feeds with metabolizable energy and essential amino acids is of paramount importance. Breeding of modern breeds and lines of pigs with high meat productivity makes it necessary to study the peculiarities of providing these nutrients for the animals. It is known that different breeds of pigs, particularly those with different productivity trends, use dietary protein in different ways. Study of features of nitrogen use by pigs of bred in the republic breeds and lines in compound feeds with different completeness of essential amino acids, in particular, lysine and its ratio with metabolizable energy, is relevant for development of standards for their amino acid nutrition in order to maximize their genetic potential of high meat productivity. The paper presents experimental materials on study of the dynamics of nitrogen deposition in body of animals, its release into environment, as well as peculiarities of deposition and use of it for the synthesis of muscle tissue in body of pigs at fattening of three genotypes - Duroc breed, Large white and Belarusian meat breeds. It has been determined that limiting factors of protein synthesis in pigs with adequate level of metabolizable energy are the intake of the required amount of available amino acids with the feed and the genetically determined rate of its deposition. Feed nitrogen was used better by pigs of the Belarusian meat breed and Duroc in comparison with pigs of Large white breed. The most efficient use of feed nitrogen was shown by gilts fed with compound feed with 0.71 g of available lysine per 1 MJ of metabolizable energy. The data obtained during the research on feed nitrogen used by animals of meat genotypes reveal the mechanism of interaction of energy and amino acid nutrition, which is of great importance for development of pig feeding standards considering the breed and trend of productivity. Acknowledgments. The research has been carried out within the framework of the State Program of applied research “Animal Breeding and Veterinary Medicine”.