Polymorphisms in TOX and NCOA 2 genes and their associations with reproductive traits in Nellore cattle

In cattle, phenotypic expression of reproductive traits occurs late in life. The identification of causal mutations in genes affecting reproduction permits the inclusion of these SNPs in customized DNA chips to increase accuracy. Therefore, the aim of this study was to detect causal mutations in the TOX and NCOA2 genes previously identified by genome-wide association studies of zebu cattle. DNA was extracted from 385 Nellore females and polymorphisms were investigated by PCR-sequencing. Five polymorphisms were detected in the NCOA2 gene and four in the TOX gene. Analysis of variance showed that a SNP in the NCOA2 gene was significantly associated with probability of early pregnancy (p=0.02) and age at first calving (p=0.03), another SNP in the same gene was significant for days to calving (p=0.03). Studies investigating polymorphisms in other regions of the gene and in other genes should be conducted to identify causal mutations.