GENE OF SOMATOTROPIN CASCADE POLYMORPHISMS, ASSOCIATED WITH BEEF PRODUCTIVITY OF KAZAKH WHITE-HEADED BREED COWS

The aim of the research was to establish the genotype asssociation of the polymorphisms bPit-1-HinfI, bGH-AluI and bGHR-SspI with the beef productivity of Kazakh white-headed cattle. The material of the studies was the blood of farm animals. Blood samples and boning data were provided by LP «Zhanabek» and LP «Karaman-K», Kostanay region. The animal genotypes were determined by polymerase chain re-action-restriction fragment length polymorphism. Statistical processing of the results of genotyping and zoo-technical data was carried out using the programs Statistica 6.0 and Microsoft Excel. Evaluation of geno-types with meat productivity was carried out according to the live weight index, and indices characterizing the physique of animals were also analyzed. The results of the studies showed that the genotype bPit-1-HinFIAA of the pituitary transcription factor-1 gene was positively associated with the stretch sign at the age of 24 months. Thus, the index of the stretch index in cows with the genotype bPit-1-HinFIAA is 132.768 (126.667; 137.500), while this indicator for cows with genotypes bPit-1-HinFIAB and bPit-1-HinFIBB is 127.966 (120.833; 137.705 ) and 119.643 (117.544; 124.074) The polymorphism bIGF-1-SnaBI is associ-ated with the sign of live weight at the age of 12, 18, 24 months (the highest value is the genotype bIGF-1-SnaBIAB and bIGF-1-SnaBIAA, the smallest is the genotype bIGF-1-SnaBIBB). Thus, the genotype bPit-1-HinFIAA can be recommended as a genetic marker for the increased meat productivity of cattle of Kazakh white-headed breed. The genotype bIGF-1-SnaBIBB is a marker of reduced meat productivity of cattle. Working with polymorphism bIGF-1-SnaBI, as with a genetic marker, should not be based on selection on a preferred genotype, but on elimination of the negative genotype bIGF-1-SnaBIBB