ASSOCIATION OF SINGLE NUCLEOTIDE POLYMORPHISMS IN THE IMMUNE-RELATED GENES WITH MASTITIS IN CROSSBRED CATTLE
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Date
2022-07-10
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COLLEGE OF VETERINARY AND ANIMAL SCIENCES, POOKODE, WAYANAD, KERALA VETERINARY AND ANIMAL SCIENCES UNIVERSITY
Abstract
Mastitis is the most prevalent and costly disease which affects the economics of the dairy farm. Even though several strategies like antibiotic therapy, improved herd sanitation, and vaccination have been tried to treat and reduce the incidence of mastitis, effective treatment and control of mastitis continue to be a major headache for the dairy farmer. Since differences in susceptibility to mastitis in cattle are known to have a strong genetic background, genetic selection for improved mastitis resistance in dairy cattle is considered to be an alternate strategy. Animal breeders often favour MAS based on the SCC or SCS to select mastitis-resistant animals.
A total of 105 lactating crossbred cattle maintained in the ILFC, Pookode of the KVASU, and two private farms located in Wayanad and Kozhikode districts of Kerala state were included in the present study. Milk samples were collected from individual quarters separately from each animal and were graded using CMT and SCC. Based on the CMT reaction, 23.81 per cent, 42.86 per cent and 33.33 per cent of animals were found to have healthy udder, subclinical mastitis and clinical mastitis, respectively. Based on SCC, 46.67 per cent, 38.10 per cent and 15.24 per cent were found to have healthy udder, subclinical mastitis and clinical mastitis, respectively.
The genotyping and polymorphism study in selected SNPs in five immune-related genes was done using the PCR-RFLP assay. The SNPs and genes included in this study were rs467234707 of gene EPS15L1, rs433539538of gene PTX3, rs45930378 of gene MAST3, rs480534837 of gene PDGFD and rs800533391 of gene STAB2. Moreover, their association with mastitis susceptibility or resistance in the population was also analyzed.
For the SNP rs467234707 of EPS15L1gene, the PCR-RFLP revealed a single banding pattern of 467bp size. Further, all the individuals were of AA genotype. The SNP rs433539538 of the PTX3 gene also revealed a monomorphic pattern with all the animals showing TT genotypes (226bp and 100bp). The SNP rs480534837 of gene PDGFD and SNP rs800533391 of STAB2 gene also showed monomorphic patterns, with GG genotype (254bp and 154bp) for SNP rs480534837 and GG genotype (76bp and 241bp) for SNP rs800533391. However, in the PCR-RFLP assay, the SNP rs45930378 of the MAST3 gene exhibited two genotypes viz.TT and TA in the cattle population under study. The frequencies of TT genotype (108bp and 220bp) and TA genotype (108bp, 220bp and 328bp) were 0.924 and 0.076, respectively and the allele frequencies for T and A were 0.962 and 0.038, respectively. The Chi-square test showed that the locus was in HWE in the populations under study. Moreover, the association study revealed that there was no association between the genotypes and udder health status (subclinical mastitis and healthy udder).