Abstract: The study covered a herd of 716 Polish Red-and-White dairy cows (a variety of Holstein-Friesian breed) kept in the Opole region, Poland. The polymorphism of a selected 297-bp GHRH gene fragment was detected by the PCR-RFLP method using specific primer sequences and endonuclease HaeIII. In the studied herd of cows, there were found to be 3 GHRH/HaeIII genotypes (GHRHAGHRHA-9.6%, GHRHAGHRHB-37.0% and GHRHBGHRHB-53.4%) determined by 2 alleles: GHRHA and GHRHB. The GHRHA allele frequency was 28.1%, whereas the GHRHB allele frequency was 71.9%. The herd under study was found to be in genetic equilibrium as the number of individuals observed in the GHRH/HaeIII genotype groups was not significantly different from their expected number calculated according to the Hardy-Weinberg law. The study proved the existence of GHRH/HaeIII polymorphism in the selected gene sequence and revealed statistically significantly higher values for the analyzed milk production traits in cows with GHRHAGHRHA genotype. The results obtained in this study suggest that the GHRH gene polymorphism might be used in the selection and breeding process to improve some milk production traits in cattle.
Marek Kmie , Inga Kowalewska- uczak , Hanna Kulig , Arkadiusz Terman , Heliodor Wierzbicki and Adam Lepczy ski , 2007. Associations Between GHRH/HaeIII Restriction Polymorphism and Milk Production Traits in a Herd of Dairy Cattle . Journal of Animal and Veterinary Advances, 6: 1298-1303.