Polymorphisms in SNP CGIL4: association stuty on the phenotype of clinical mastitis resistance in Holstein cows

Abstract

Bovine mastitis is the most important udder pathology and have a significant economic impact in the dairy industry. Its etiology is associated to problems with health and milking management. However, there are animals with resistance or susceptibility to mastitis, even when environmental factors are controlled. Recently, some molecular markers were associated to the phenotype of resistance to mastitis. The present study aims to verify if, based on clinical history of cows of second and third lactation, the SNP CGIL4 is associated to the phenotype of resistance to mastitis in Holstein cows in a herd in southern Brazil. Genomic DNA was obtained from blood samples of 160 Holstein cows (second and third lactation) from dairy herds from Rio Grande do Sul state, Brazil. Phenotype of resistance or susceptibility to clinical mastitis was defined based on animal’s clinical history, and the animal was classified as susceptible if presented at least 3 episodes of clinical mastitis during the last lactation. The identification of the CGIL4 SNP was performed using a PCR-RFLP. The association between genotipes and phenotipes was acessed by the χ 2 test. To detect polymorphism, Polymerase Chain Reaction (PCR) was performed using a touch-down PCR reaction producing an amplicon of 399 bp. The Restriction Fragment Length