Assessment Of Pairwise Combinations’ Association Of Polymorphic Variants Of The Genes Of Bpit-1, Bgh, Bghr Bigf Somatotropic Cascade With Meat Productivity Of The Cattle Bred In Kazakhstan

Abstract

Assessment of the genetic potential in efficiency of agricultural animals by genetic markers is a modern, popular and rapidly developing area in breeding. Currently, effective genetic markers are searched for among the candidate genes for various traits in various breeds. It has been assumed that the phenotypic effect of genetic markers may be more pronounced if the genotype of the animal has genetic markers that potentate the effect of each other. Therefore, genes of the somatotropic cascade have been taken for the study, the protein products of which are key links in the humoral chain involved in the processes of mammals’ growth and development (bPit-1, bGH, bGHR, bIGF-1). In this case, expression of one gene affects expression of all other genes, and one polymorphism can potentiate the action of another one. The subjects of the study are polymorphic genes of the somatotropic cascade: bPit-1, bGH, bGHR and bIGF-1. Meat productivity of animals with various genotypes and their pairwise combinations was assessed based on live weight at the age of 18 and 24 months. Results of this work show that genetic markers that are diplotypes often have more pronounced phenotypic effect than individual marker genotypes. For example, the range of live weight at the age of 12 months for IGF-1BB genotype is 325-331 kg, its pairwise combination with bGH-AluILL genotype potentiates this effect to 278-306 kg; genotypes that are individually associated with meat productivity in pairwise combinations have increased or decreased statistically significant phenotypic effect, compared to the total sample. Such combinations may be applied as genetic markers of productivity in breeding programs. An example is bGH-AluI polymorphism. Inversely, polymorphisms that individually show association with a symptom of productivity may be within the total sample in pairwise combination by the phenotypical effect.