Genome-wide scans identify novel and known genomic regions affecting fertility in Bonga sheep - a prolific sub-Saharan African sheep

Abstract

Maximizing the number of offspring born per female (reproductive efficiency/success), is an important trait in the livestock industry that is closely associated with fertility traits. However, fertility is a complicated trait, and little is known about the regions of the genome influencing it in most livestock species. We conducted a selection signature analysis using genome-wide genotype data from the prolific Bonga sheep in Ethiopia and identified 41 candidate regions associated with fertility and reproduction traits. The analyses confirmed the presence of selection signatures in genomic regions that span or lie adjacent to two genes, GDF5 and BMP15, that are known to be associated with prolificacy. We also identified several candidate regions that spanned several genes underlying female and male reproduction physiology that have never been reported before in prolific sheep. These include maintenance of pregnancy, reproduction function, ovarian fertility, follicular growth and development, early pregnancy success and transcriptional regulation during embryogenesis in females and spermatogenesis and testicular maturation in males and in general fertilization and conception success. The results reported herein provide, for the first time, the findings of a genome-wide scan providing insights into the genetic basis of fertility and therefore reproductive success in a sub-Saharan African breed of sheep. They confirm the complexity of the genetic mechanisms underlying fertility and hence reproduction success while demonstrating that the underlying genetic basis of prolificacy is a function of the major genes with minor effects as well as multiple other genes enhancing male and female reproductive function.