Progress on major genes for high fecundity in ewes

Abstract

The existence of major genes affecting fecundity in sheep flocks throughout the world has been demonstrated. Three major genes whose mutations can increase ovulation rate have been discovered, and all related to the transforming growth factor β (TGF-β) superfamily. The mutant FecB of bone morphogenetic protein receptor 1B (BMPR1B) has an additive effect on ovulation rate. Six mutations (FecX^I, FecX^H, FecX^G, FecX^B, FecX^L, FecX^R) of bone morphogenetic protein 15 (BMP15) related with fertility have been identified that share the same mechanism. All the mutants can increase ovulation rate in heterozygotes and cause complete sterility in homozygotes. Homozygous ewes with two new mutations (FecX^Gr, FecX^O) of BMP15 had increased ovulation rate without causing sterility. There are five mutations in growth differentiation factor 9 (GDF9) associated with sheep prolificacy where FecG^E and FecG^F have additive an effect on ovulation rate and litter size. The newly identified β-1,4-N-acetylgalactosaminyltransferase 2 (B4GALNT2) gene of FecL is proposed as a new mechanism of ovulation rate regulation in sheep. Woodlands is an X-linked maternally imprinted gene which increases ovulation rate. In addition, several putative major genes need to be verified. This review is focused on the identification of the mutations and mechanisms whereby the major genes affecting ovulation rate.

Keywords

major gene / ovulation rate / sheep / reproduction

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Acknowledgements

This work was funded by the Agricultural Science and Technology Innovation Program of China (ASTIP-IAS13), Key Technology Research and Development Program of Xinjiang Uygur Autonomous Region of China (200891102 and 2013911056), and the Earmarked Fund for China Agriculture Research System (CARS-39).

Compliance with ethics guidelinesƒQiuyue Liu, Zhangyuan Pan, Xiangyu Wang, Wenping Hu, Ran Di, Yaxing Yao and Mingxing Chu declare that they have no conflict of interest or financial conflicts to disclose.ƒThis article is a review and does not contain any studies with human or animal subjects performed by any of the authors.

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