The influence of BoLA-DRB3 alleles on incidence of clinical mastitis, cystic ovary disease and milk traits in Holstein Friesian cattle

Abstract

The major histocompatibility complex in cattle (BoLA) is regulated by genes that are closely related to the development of the immunological response to pathogens. The most polymorphic BoLA-DRB3.2 locus was analysed in 209 black-and-white Holstein-Friesian cows in Poland in order to a better explanation of influence of MHC on immunity to diseases in dairy cattle. A total of 23 alleles were identified, among which the *24, *16 and *22 alleles were observed with the highest frequency. These alleles were analysed in terms of their association with the occurrence of mastitis, ovarian cysts, retained placenta and uterine abscesses as well as their contribution to production traits (milk yield, protein and fat percentage in milk). It was determined that the BoLA-DRB3.2 *22 and *16 alleles were associated with a lower risk of clinical mastitis; however, a statistical significance was observed only for the *22 allele. Clinical mastitis was observed at a frequency lower by 8% in cows with one copy of the *22 allele compared to cows with 0 copies of the allele. The presence of the *22 allele in the genotype was also associated with higher milk yield, although this association was not statistically significant.

Single-step genome-wide association for longitudinal traits of Canadian Ayrshire, Holstein, and Jersey dairy cattle

“…Interestingly, we identified an association of BoLA with MY, PY and FY, but not with SCS. Pokorska et al (2018) also identified a higher MY for a specific allele in Holstein cattle. The BOP1, DGAT1, EEF1D, FBXL6, and PTK2 genes were suggested as candidate genes only for the first lactation.…”

Copy number variations in BOLA‐DQA2, BOLA‐DQB, and BOLA‐DQA5 show the genomic architecture and haplotype frequency of major histocompatibility complex class II genes in Holstein cows

“…[32][33][34] However, the score for the current genomic selection might not reflect most BoLA alleles although various economic traits of cattle were associated with the BoLA alleles. 3,35,36 Because the SNP array could not set the probes in the complicated genomic regions, including the coding regions of BoLA genes, to determine the BoLA alleles. Therefore, the imputation method to detect the BoLA alleles using the SNP data and the LD values among the correct BoLA alleles, which we elucidated in the present study, would be useful for a more accurate genomic selection.…”

“…The progress in genotyping using the SNP array and WGS has successfully accelerated the implementation of genomic selection to identify genetically superior cattle at an earlier age 32‐34 . However, the score for the current genomic selection might not reflect most BoLA alleles although various economic traits of cattle were associated with the BoLA alleles 3,35,36 . Because the SNP array could not set the probes in the complicated genomic regions, including the coding regions of BoLA genes, to determine the BoLA alleles.…”

“…The gene symbols in the major histocompatibility complex (MHC) class IIa region include BOLA‐DQA2 (DQA2, ENSBTAG00000009656), BOLA‐DQB (DQB2, ENSBTAG00000021077), BOLA‐DQA5 (DQA5, ENSBTAG00000038128), BLA‐DQB (DQB1, ENSBTAG00000019588), LOC100848815 (DQA1, ENSBTAG00000037605), and BOLA‐DRB3 (DRB3, ENSBTAG00000013919) 2 . Particularly, DRB3 alleles were associated with proviral load in bovine leukemia virus (BLV) infection 3‐5 and somatic cell count in milk in mastitis 6,7 owing to their effects on interindividual immune responses 8,9 . Additionally, DQA1 was reportedly associated with proviral load in BLV infection 10 .…”

“…Particularly, DRB3 alleles were associated with proviral load in bovine leukemia virus (BLV) infection [3][4][5] and somatic cell count in milk in mastitis 6,7 owing to their effects on interindividual immune responses. 8,9 Additionally, DQA1 was reportedly associated with proviral load in BLV infection.…”