GROWTH HORMONE GENE POLYMORPHISM (LEU127VAL) IN DAIRY AND BEEF CATTLE (REVIEW)

Abstract

The study of single nucleotide polymorphisms (SNPs), which are places in
DNA where one nucleotide is replaced by another, can be useful for understanding of the effect on various phenotypic manifestations of traits in animals. The purpose of our work was to
collect and analyze scientific data on the current state of growth hormone gene polymorphism
associations, genotypes and alleles distribution in various domestic cattle breeds. When discussing scientific data, we used the results of studies that were published in the open press
over the past 5 years. The bovine growth hormone gene is localized on the 19th chromosome
and consists of five exons and four introns. The most studied was the polymorphism that
caused the substitution of the leucine amino acid instead of valine at position 127 of the synthesized polypeptide chain (GH-L127V) in the 5th exon. Different authors' data on the distribution of genotypes and alleles at the growth hormone gene locus (GH/AluI) varied significantly. In all the studied breeds, the frequency of occurrence of the GH_L allele significantly
exceeded the frequency of the GH_V allele and ranged from 0.60 to 0.98. The obtained results
also showed a tendency that almost all breeds had a high distribution of the homozygous
GH_LL genotype, however, in the sample of crossbred bull calves from the Kalmyk and Red
Angus breeds of American selective breeding, the heterozygous GH_LV genotype prevailed.
The study of single nucleotide polymorphisms is a kind of indicator for producers of beef and
dairy cattle. During the selection process, the obtained data allow us to make more rational
decisions when selecting animal individuals with desirable genotypes.