The Reproductive Traits of Sheep and Their Influencing Factors

Abstract

In farm animals, both genetic and non-genetic factors affect reproductive traits. These factors can be categorized as intrinsic and extrinsic. Extrinsic factors relate to the animal’s environment, while intrinsic factors are related to its genotype. Various reproductive traits are studied concerning age, season, management, nutrition, body score, and birth type. In addition, genetic variations of the transforming growth factor-β (TGFβ) superfamily including BMPR-1B, BMP15, and GDF9 have been studied for their effect on sheep reproduction. Numerous other genes that affect reproductive characteristics in sheep have also been identified, including melatonin receptor 1A, SLC5A1, CCNA1, ABCC1, insulin-like growth factor-I (IGF-1), leptin receptor, prolactin, GREM1, and numerous other new candidates. These reproductive traits vary based on differences in environmental conditions and the genetic composition of livestock. Genetic and environmental factors that influence livestock traits can be improved by understanding those factors, but genetic and phenotypic associations that affect livestock traits are scarce. Accurate genetic evaluation and development of breeding goals require a more accurate evaluation of genetic parameters, in particular correlations with phenotypic traits. As a result, understanding how genetic and environmental factors interact becomes critical to developing efficient and effective management plans for sheep. This review provides insight into the factors that influence sheep reproductive performance.