Contribution of the mutation rs8193069 in TLR4 to mastitis resistance and performance in Holstein cows in southern China

Abstract

Bovine mastitis has become increasingly important issues for farmers and consumers, leading to large economic losses in the dairy industry worldwide. Because treatment of mastitis is difficult and costly, improved mastitis resistance through selective breeding would be advantageous. The toll‐like receptor 4 (TLR4) is an important player in recognising pathogens and activating immune responses. However, its roles in mastitis occurrence and the underlying molecular mechanisms are unclear. In this study, a single nucleotide polymorphism, rs8193069 (T → C) in TLR4 gene was detected in a Holstein cow resource population in southern China. Association analysis with 5‐year production traits, haematology, and biochemistry parameters revealed that individuals with genotype CC had significantly lower somatic cell counts (SCC), lower fat percentage, but higher 305‐day milk (p < 0.05) and total milk yield (p < 0.01). Both genotypes CC and CT had lower lymphocyte counts (#LYMPH) (p < 0.01) and basophil counts (#BASO) (p < 0.05) than TT. Genotype CC had a less level of triglyceride (p < 0.01) and creatine kinase (p < 0.05) than CT. Further analysis based on the production data revealed significant positive correlations between SCC and #LYMPH. Analysis of TLR4 protein structure and properties suggested that the missense mutation on the 674th amino acid from Thr to Ile reduced the flexibility and hydrophilicity of TIR domain, implying a weakened binding ability of TLR4 to its adaptors. In conclusion, allele C of rs8193069 was the major allele in Holstein cows that indicated a greater genetic potential to mastitis resistance and milk yields, probably via the LPS‐TLR4 inflammatory signalling. This study offers a marker to improve mastitis resistance in the dairy cow population in southern China.

Polymorphism of TLR1, TLR4, and SLC11A1 genes in populations of different cattle breeds of Ukrainian selection

“…For instance, in most cases, different populations are characterized by high allele C frequency, which may be related to ongoing breeding work in the direction of increasing milk productivity parameters. The association of the C allele with the milk production traits of Holstein cows was confi rmed in a study by Chen et al (Chen H et al, 2021). At the same time, in the work of other authors, actually parity values of the C and T allele frequencies for this locus were revealed for Lithuanian Holstein cattle (Mišeikienė R et al, 2020).…”

Hematology Reference Intervals for Holstein Cows in Southern China: A Study of 786 Subjects

“…The time interval between vaccination and blood collection for each cow was of at least 30 days. Blood sample collection and hematology tests were performed as described previously [ 14 ]. To be more specific, blood samples from the cows were collected via coccygeal vein using a 10 mL disposable blood collection container for animals (SanMen MinSheng Medical Appliances Co., Ltd., Taizhou, China) connected to EDTA tubes (Wuhan Zhiyuan Medical Treatment Technology Co., Ltd., Wuhan, China).…”

Genetic polymorphisms in immune- and inflammation-associated genes and their association with bovine mastitis resistance/susceptibility

“…Furthermore, Wang et al (143) reported that the LPS, which is considered an essential PAMPS, could be found in most gram-negative and some gram-positive bacteria that interact with TLR4 in mammary epithelial cells, which is why the higher expression of TLR4 has been noticed during mastitis in dairy cattle (143). A study reported that SNP-rs8193069 in the TLR4 gene was significantly associated with higher milk SCC (145,146). Similarly, another study found that the SNP-1,397-C-T at exon 3 of TLR4 correlated with milk SCS in Chinese Holstein, Sanhe cattle, and Chinese Simmental (145, 147).…”