DRB3 Gene Polymorphism and Somatic Cell Count in Milk of Jersey Cows

The aim of this study was to investigate associations between BoLA-DRB3 polymorphism and Somatic Cell Count (SCC) in milk, daily milk yield and milk fat and protein percentage content. DNA used in the study was obtained from 184 Jersey cows from Wielkopolska region in Poland. The frequencies of DRB3/HaeIII alleles and genotypes were determined. Four alleles of the following frequencies were found: A-0.560; B-0.195; D-0.008 and E-0.236. The association between DRB3/HaeIII polymorphism and SCC (transformed into a logarithmic scale) was analysed with regard to parity, season, stage of lactation, year of study and cow as sources of variability. Statistically significant associations were found with regard to all the analysed factors. The highest SCC was recorded in milk of EE-genotype cows, whereas the lowest SCC was found in BB-genotype cows. The study also included the effect of DRB3/HaeIII genotype on daily milk yield and fat and protein content in milk. DRB3/HaeIII genotype was found to be non-significant for these traits. The results obtained in this study suggest that BoLA-DRB3 is a candidate marker for SCC and, consequently, for mastitis re sistance/susceptibility in dairy cows.