Association of bovineCD4andSTAT5bsingle nucleotide polymorphisms with somatic cell scores and milk production traits in Chinese Holsteins

Abstract

CD4+T cells play a key role in the immune response of pathogen-induced mastitis in dairy cattle. Mammary gland factor STAT5b is involved in the regulation of CD4+T cell differentiation during inflammatory response and milk production. Little is known about the genetic variation effects of bovineCD4andSTAT5bgenes on somatic cell score (SCS) and milk production traits in dairy cattle. The aim of the study was to investigate the single nucleotide polymorphisms (SNPs) of bovineCD4andSTAT5bin Chinese Holsteins and to analyse their association with estimated breeding values (EBVs) for SCS and milk production traits. In the present study, SNPs ofCD4(NC_007303 g.13598C>T) andSTAT5b(NC_007317 g.31562 T>C) were identified and genotyped in Chinese Holstein population. The results showed that both SNPs were significantly associated with the EBVs for milk yield and protein yield in Chinese Holstein cows, and the SNP inCD4was associated with the EBV for SCS (P<0·01). The additive effect ofCD4SNP on protein yield was significant (P<0·05), and the dominant effect ofSTAT5bSNP was significant on milk yield and protein yield (P<0·01). Cows with combination genotype C7 (CCTT:CD4g.13598C>T andSTAT5bg.31562 T>C) had the highest SCS EBV but lower milk yield, while cows with C2 (TTTC) produced more milk, fat and protein than the other eight combination genotypes. These results suggested that the SNPs inCD4andSTAT5bmay be potential genetic markers for SCS and milk/protein yields selecting and warrant further functional research.