Association of polymorphism in Exon 3 of toll-like receptor 4 gene with somatic cell score and milk production traits in Holstein dairy cows of Iran

Abstract

Mastitis is a complex inflammatory disease of the mammary gland that is caused by the invasion of pathogens. This leads to reduced synthetic capacity, compositional changes and increased somatic cell counts (SCC) in milk. Toll-like receptor 4 (TLR4) is a cell surface receptor that recognizes lipopolysaccharides (LPS) of gram-negative bacteria. Its role in pathogen recognition and the subsequent immune response and differential expression of the gene during mastitis have prompted the investigation of TLR4 gene as a candidate to improve mastitis resistance in dairy cattle. The aim of this study was to analyse the possible association of a single nucleotide polymorphism (SNP) in putative co-receptor-binding region 2 (T4CRBR2) of the TLR4 gene with somatic cell score (SCS) and milk-related traits in 408 Iranian Holstein cows. The polymerase chain reactionrestriction fragment length polymorphism (PCR-RFLP) technique was performed for genotyping. The effect of the genotype on the traits of interest was analysed using the general linear model (GLM) procedure of SAS software. The B allele frequency was 0.634 and the distribution of genotypes was not in Hardy-Weinberg equilibrium in the overall population. The B allele of the SNP was associated with higher 305-day milk yield and breeding value for milk yield, and lower fat percentage and lower SCS, as compared with allele A. The association between TLR4 polymorphism with SCS and milk production traits reported in this study suggests that this SNP has the potential to be used as a marker for selection, based on molecular information.

Genetic Polymorphisms inLTF/EcoRI andTLR4/AluI loci as candidates for milk and reproductive performance assessment in Holstein cattle

“…The alleles controlled the occurrence of three genotypes (AA, AB and AB) with frequency of 0.40, 0.38 and 0.22. The allele and genotype frequencies obtained in the present study were dissimilar to the findings of Wang et al () and Noori et al () who reported frequencies of 0.42, 0.44 and 0.45 for allele A and 0.58, 0.56 and 0.55 for allele B. Shimizu et al () used the same set of primers for examining the TLR4 gene polymorphism of in 200 Holstein dairy cows from the Obihiro University. In the latter study, only two genotypes (AB and BB) were detected, which is dissimilar to that the denoted genotypes in our study.…”

“…Wakchaure et al () cited genetic polymorphism in TLR4 gene and its association with incidences of mastitis in Sahiwal cattle. Noori et al () and Li et al () indicated this association with somatic cell score and milk performance traits in Holstein dairy cows. Zhou et al () reported also that the phenotypic variation in milk traits of dairy cows in pasture‐fed New Zealand (NZ) Holstein‐Friesian × Jersey (HF × J) cross dairy cows was attributed to TLR4 gene polymorphism.…”

“…Several polymorphisms have been identified in bovine TLR4 gene (White et al, ) which are reported to affect SCS, be associated with estimated breeding values for lactation persistency and also revealed an association of E3+2021 with milk fat and protein percentage in late lactation in Holstein‐Friesian, Jersey, Norwegian Red, Montbeliarde and Holstein‐Friesian × Jersey cows (Beecher et al, ; Sharma, Leyva, Schenkel, & Karrow, ; Wang, Xu, Gao, Ren, & Chen, ). Many studies reported the association between bovine TLR4 gene and somatic cell score and susceptibility/resistance of many dairy cow diseases (El‐Shafaey et al, ; Li et al, ; Noori et al, ); however, few literatures reported such association with reproductive performance traits (Goldammer et al, ; Shimizu et al, ; Werling & Jungi, ).…”

The influence of TLR4 gene polymorphisms on milk quality and composition of Lithuanian Holstein cows

“…Our study was carried out to analyse three polymorphisms of the TLR4 gene and to determine their possible associations with SCC and milk composition traits in Holstein cows. Noori et al (2013) showed the T allele in c.9421C>T was associated with lower fat percentage and lower SCS when compared to allele C. Our results obtained frequency of allele T dominated in c.9421C>T. Cows homozygous with T allele produced milk with the lower fat content (4.03 %) but lactose content was the biggest (4.62 %) by following homozygous C allele although no reliable associations have been identified. Zhou et al (2017) reported also that the phenotypic variation in milk traits of dairy cows in pasture-fed New Zealand (NZ) Holstein-Friesian× Jersey (HF×J) cross dairy cows was attributed to TLR4 gene polymorphism.…”

“…Sharma et al (2006) described an association between TLR4 and lactation persistency in Canadian dairy cattle, while in Irish cattle Beecher et al (2010) found an association between variation in TLR4 and milk fat and protein percentage. In Iranian Holstein cattle Noori et al (2013) described an association between TLR4 exon 3 variation, and somatic cell score and milk-related traits, while Zhou et al (2017) have determined how polymorphisms of the TLR4 gene influences milk fat content in Chinese Holstein cows. Based on the findings of Ogorevc et al (2009) who examined the role of TLR4 in pathogen recognition and subsequent initiation of the inflammatory and immune response, and on differential expression of the gene during mastitis, TLR4 has been proposed as a candidate for increasing mastitis resistance in breeding programs.…”