Polymorphisms of Growth Hormone and Calpastatin Genes and Their Association with Sheep Meat Quality

Abstract

The sheep breeeding for meat is of great interst at present due to rising meat intake among people. Over the recent decade, selective breeding with molecular markers has provided the opportunity to improve the sheep muscular system and the carcass weight and yield with decreasing the fat accumulation. Recognition of genes affecting the characteristics of farm animal products has allowed the researchers to identify single nucleotide polymorphisms (SNPs) associated with phenotypic traits improving the productive performance of livestock. Alleles of genes calpastatin (CAST) and somatropin, the synthetic form of growth hormone (GH) can represent the potential markers for sheep meat productivity. The objective of the survey is to study polymorphic variants of the CAST and GH genes in meat and wool sheep of the genotype of cross 1/2 Poll Dorset ×1/2 North-Caucasian meat-and-wool breed, reared in the Stavropol krai and their relationships with the traits important in meat production. Sheep genotyping for the somatotropin and calpastatin genes was performed with the method of PCR restriction fragment length polymorphism (PCR-RFLP). The evaluated genes were polymorphic. Three genotypes (AA, AB, and BB) of gene GH and two genotypes (MM and MN) of gene CAST have been identified. Genotypes AB and MM were characterised by the highest frequency of occurrence (42.8 and 87.9%, respectively). The highest values for meat production were recorded in the ewes with the AB, BB, and MN genotypes. The slaughter weight of specimens with genotype MN of the CAST gene was greater than that in the sheep with homozygous genotype (MM) by 5.9% and in the animals with genotypes AB and BB of gene GH, compared to the ewes with genotype AA, by 6.8 and 7.5%, respectively. The animals with genotypes indicated above were more efficient than their peers were in the muscle-tissue protein contents by 0.6, 3.5, and 1.5%.