POLYMORPHISM OF SOMATROPIN CASCADE GENES IN JERSEY COWS

This article presents the results of a study of somatotropin cascade gene polymorphisms (GH - somatotropin, PRL - prolactin, PIT1 - pituitary transcription factor) in first-calf Jersey cows. Allelic variants of PRL, PIT1 and GH genes were identified by polymerase chain reaction followed by restriction fragment length polymorphism (PCR-RFLP), using the restriction endonucleases Alu I, RsaI and HinfI. Restriction results were identified by agarose gel electrophoresis. The frequency of alleles and genotypes was determined according to E.K.Merkurieva, the observed and expected distributions were calculated using the Hardy-Weinberg method, and the indices of genetic equilibrium, inbreeding coefficients and polymorphism informativeness were calculated. It was established that A (0.71) allele and AA (48.3%) and BB (44.8%) genotypes predominate for PRL gene, B (0.78) allele and BB (63.2%) genotype predominate for PIT1 gene, L and V allele frequencies are 0.53 and 0.47, respectively, for GH gene with LV genotype being dominant (52.9%). All the studied loci are in the Hardy-Weinberg equilibrium state (χ² < 3.84). Negative values of inbreeding coefficients indicate an excess of heterozygotes, which may be associated with the manifestation of heterotic effect and selection in favor of heterozygous animals. The most polymorphic locus among the studied loci is the GH locus (PIC=0.374), followed by the PRL (PIC=0.329) and PIT1 (PIC=0.287) loci. All three loci are characterized by moderate informativeness for breeding. The obtained results can be used to develop marker-assisted selection programs for Jersey breed.