Association between BoLA-DRB3 and somatic cell count in Holstein cattle from Argentina

Different studies have proved that the resistance/susceptibility to mastitis is genetically determined. The major histocompatibility complex in cows is known as bovine lymphocyte antigen (BoLA). Genes from the BoLA have been associated with the occurrence of infectious diseases such as mastitis and leukosis, especially the BoLA-DRB gene. The object of the present study was to detect associations between BoLA-DRB3 alleles and somatic cell count (SCC), as an indicator of resistance/susceptibility to mastitis in Holstein cattle (N = 123) from La Pampa, Argentina. Fisher's exact test and Woolf-Haldane odds ratio were applied to study the association between SCC and BoLA-DRB3 allele frequencies. Significant association was noted between BoLA-DRB3.2*23 and *27 alleles (p < 0.05) and protective or susceptibility effects, respectively. In addition, alleles BoLA-DRB3.2*20 and *25 exhibit suggestive association with high SCC (p < 0.1). These results were partially in agreement with data reported from Japanese Holstein cattle, but differed from those published by other authors. A possible explanation for the contrasting results could be that the mastitis is a multifactor disease caused by different pathogens. Moreover, most of the studies were carried out using PCR-RFLP method, which has less resolution than PCR-SBT because PCR-RFLP defined alleles included more than one sequenced alleles.