Polymorphism of the IGF-1 gene in the livestock of Holstein cows breeds and breeding bulls

Insulin-like growth factor-1 (IGF-1), secreted in the liver, is one of the major elements of the somatotropic axis, is involved in numerous physiological processes, and plays a role in the control of lactation, mammary gland development, and the formation of important performance traits such as growth and reproductive traits. The associations of IGF-1 gene polymorphism (T → C 512) have been studied and evaluated with economically useful traits in different breeds of dairy and beef cattle. The study carried out on the population of Holstein cows and Holstein and Holsteinized bullssires allowed to establish that the identified populations are polymorphic, the animals are represented by three genotypes of IGF-1 gene. The frequency of occurrence of IGF-1 gene genotypes in the cow population amounted to: AA - 24.7 %, AB and BB - 55.6 and 27.3 %, and in bulls-sires: AA – 31.3 %, AB – 49.3 % and BB – 19.4 %. In both cases, the predominance of the “normal” allele over the “mutant” allele was observed, with the A allele prevailing over the B allele to a greater extent in the group of breeding bulls. The analysis of literature data indicates that the frequency of alleles ( A and B ) and genotypes ( AA , AB and BB ) in populations shows variation depending on breed, direction of productivity and habitat of cattle.