Current status of nonsurgical embryo transfer in swine

Embryo transfer in pigs is a reproductive technology with great potential because it enables the movement of high-value genetic material, in the form of embryos, with reduced transport costs and no health risks. However, its use has been limited for decades despite significant interest, primarily due to the need for laparotomy for embryo collection from donors and deposition into recipients. Over the past 30 years, various procedures have been developed to deposit embryos nonsurgically in the body of the uterus with promising results, but none sufficiently successful. Because the uterine body is not the ideal site for embryo deposition at the morula and blastocyst stages, a new method that is capable of depositing porcine embryos deep into the uterine horn has been developed. This nonsurgical deep uterine method is a simple, effective, and well-tolerated technique in gilts and sows, achieving high fertility and prolificacy using fresh, stored, and vitrified–warmed embryos under field conditions. The present review provides a brief overview of the current status of nonsurgical deep uterine embryo transfer and addresses the varied reproductive performance observed across farms when this technology was applied in commercial programs. In addition, several future directions for its on-farm commercial application are discussed.