Embryo Biotechnologies in Sheep and Goats: Current Advances, Limitations, and Integration with Genomic Selection

Abstract

Sheep (Ovis aries) and goats (Capra hircus) collectively support the livelihoods of hundreds of millions of people in the developing world, providing meat, milk, fibre, and hides in agro- ecosystems that are often too arid or marginal for other livestock species. Despite their global importance, the application of reproductive biotechnologies to accelerate genetic improvement in small ruminants has lagged substantially behind progress in dairy cattle, constrained by unique anatomical barriers (the tortuous caprine and ovine cervix), marked reproductive seasonality, smaller commercial scale, and limited investment in research infrastructure relative to the bovine industry. This review comprehensively examines the current status and technical constraints of the major embryo biotechnologies applicable to sheep and goats: superovulation and embryo transfer (MOET), ovum pick- up- based in vitro production (OPU- IVP), embryo cryopreservation, sexed semen application, somatic cell nuclear transfer, and the emerging integration of embryo technology with genomic selection (OPU- IVF- GS). For each technology, the biological and logistical factors influencing performance are critically evaluated, empirical performance benchmarks are synthesised, and practical implementation guidance for both research and field settings is provided. The review also evaluates the evidence for using melatonin supplementation, out- of- season breeding, and laparoscopic approaches to overcome the major constraints of seasonality and cervical anatomy. Finally, the potential for combining OPU- IVF with genomic embryo selection to accelerate genetic gain in small ruminant breeds is assessed in the context of recent pilot implementations.