PSXIV-18 Genome-wide association study to identify genomic regions and single nucleotide polymorphisms functionally associated with bull fertility.

摘要

Many beef producers select their animals for production traits such as carcass weight or tenderness; however, this may result in a loss of highly reproductive traits. In order to keep up with the production and demand of beef products, the proportion of calves born needs to increase accordingly. The most effective and cost-efficient way to achieve this is by researching the potentials to improve bull fertility, as it is known to play an important role in increasing herd size. Contrary to cow fertility traits, many fertility related traits in bulls (such as semen volume, motility, and scrotal circumference (SC)) are moderately to highly heritable (ranging from 0.29 to 0.78) and therefore are significantly influenced by genetics. We performed a genome-wide association study (GWAS) to identify genomic regions and single nucleotide polymorphisms (SNPs) significantly associated with SC in crossbred beef bulls and candidate genes related to bull fertility. The population in our study included 267 purebred and crossbreed beef bulls that had been previously genotyped with the Affymetrix GeneChip® Bovine Genome High Density Array. Bulls were 139 months of age on average, and had an average SC of 36.64 cm. Genotype quality control was performed, resulting in a final marker set of 421,354 SNPs distributed across the 29 autosomes. Preliminary results showed two SNPs significantly associated with SC, AX-20927056 and AX-20927088, both of which were located on chromosome 16. Furthermore, a haplotype-based GWAS identified two haplotype blocks significantly associated with SC on chromosomes 3 and 4, which are located in and respectively. Both of these genes are involved in regulating sex and reproduction processes and therefore are candidate genes influencing SC. Further analysis will identify if there is a correlation with other bull fertility traits such as motility measurements.