Association of the <i>BoLA-DRB3</i> alleles with estimated breeding value for somatic cell count in Polish dairy cattle

Introducing resistance to mastitis into breeding programmes for dairy cattle seems to be one of the possible methods for limiting the increasing number of mastitis cases. Looking for candidate genes for genetic markers is one of the strategies. The BoLA–DRB3 alleles have considerable promise as potential mastitis marker. The objective of the study was to evaluate relationships between two BoLA–DRB3 alleles (BoLA–DRB3.2*16 and BoLA-DRB3.2*23) and estimated breeding value (EBV) for somatic cell count (SCC) in Polish dairy cattle. A total of 525 Polish Holstein cows in two experimental farms were evaluated for test-day SCC. The polymorphism of BoLA–DRB3 gene was identified using the MPT-PCR method. The variance components for test-day SCC were estimated by the REML method using animal model. The breeding value of SCC was calculated according to the BLUP method. Linear contrast between model-adjusted breeding values of SCC for all animals was used to test for differences between genotypes. In Polish Holstein cows population BoLA allele DRB3.2*23 was associated with increase of EBV for SCC in milk. It was observed increase of EBV for SCC from cows carrying this allele comparing to cows carrying BoLA–DRB3.2*16 (p ≤0.07) or other alleles (p ≤0.01).