Surgical embryo collection but not nonsurgical embryo transfer compromises postintervention prolificacy in sows

Recent advances in nonsurgical deep uterine (NsDU) embryo transfer (ET) technology allow the noninvasive transfer of porcine embryos into recipients, overcoming the most important impediment for commercial ET in this species. Although many factors in the porcine ET-field have been recently evaluated, many others remain to be explored. We investigated here the future reproductive performance of donors and recipients after artificial insemination subsequent to the default surgical embryo recovery approach and to the NsDU-ET procedure, respectively. Although surgical embryo collection did not influence subsequent farrowing rates (90.5%), litter size decreased severely (8.9 ± 0.8 piglets) compared to presurgery (10.8 ± 0.3 piglets) and control group (10.7 ± 0.3 piglets). In contrast, NsDU-ETs did neither affect fertility nor prolificacy of recipients in the cycle subsequent to ET, regardless of whether they were pregnant after NsDU-ET or not. These results indicate that while the surgical embryo collection procedure compromises the reproductive future of donor sows, the NsDU-ET approach does not affect the reproductive potential of the recipients after reintroduction to the breeding stock of the farm. Further research is thus needed to improve surgical embryo collection.