Simple SummaryIn order to improve animals’ resistance to mastitis in subsequent generations and to reduce disease prevalence, one feasible approach could be the genomic selection of cows with the most potentially protective immune responses. In this study, 298 cattle were genotyped for 89 single nucleotide polymorphisms through the Kompetitive Allele Specific PCR. Our findings reveal a significant association of a molecular marker in theBOLA-DRB3gene with mastitis prevalence in the investigated breeds. This supports previous studies that theBOLA-DRB3gene represents an important locus affecting resistance to mastitis in cattle. These results contribute to an increase in knowledge and available data regarding the genetic variability of SNPs for udder health in cattle.AbstractMastitis is the most common production disease in the dairy sector worldwide, its incidence being associated with both cows’ exposure to bacteria and the cows’ genetic make-up for resistance to pathogens. The objective of our study was to analyse 89 missense SNPs belonging to six genes (CXCR2, CXCL8, TLR4, BRCA1, LTF, BOLA-DRB3), which were found to be associated with genetic resistance or susceptibility to mastitis. A total of 298 cattle (250 Romanian Spotted and 48 Romanian Brown) were genotyped by Kompetitive Allele Specific PCR (KASP) and a chi-squared test was used for genetic association studies with clinical mastitis. A total of 35 SNPs (39.3%) among the selected 89 SNPs were successfully genotyped, of which 31 markers were monomorphic. The polymorphic markers were found in two genes:TLR4(rs460053411) andBOLA-DRB3(rs42309897, rs208816121, rs110124025). The polymorphic SNPs with MAF > 5% and call rates > 95% were used for the association study. The results showed that rs110124025 in theBOLA-DRB3gene was significantly associated with mastitis prevalence (p≤ 0.05) in both investigated breeds. Current results show that the SNP rs110124025 in theBOLA-DRB3gene can be used as a candidate genetic marker in selection for mastitis resistance in Romanian dairy cattle.