Non-surgical deep intra-uterine transfer of in vitro produced porcine embryos derived from sex-sorted frozen–thawed boar sperm

Embryos and offspring of a pre-determined sex have been produced in pigs using AI and IVF with unfrozen sperm, and after surgical insemination with sex-sorted frozen–thawed sperm. The aims of this study were to demonstrate that sex-sorted frozen–thawed boar sperm could be incorporated into pig IVF for the production of embryos of a pre-determined sex and that these embryos could be successfully non-surgically transferred. Oocytes were matured in vitro, fertilised with either unsorted or sex-sorted frozen–thawed sperm and cultured until the eight-cell stage. These embryos were then transferred to recipients (n = 7) non-surgically (n = 70 embryos per sow). Oocyte cleavage was similar between sex-sorted (1538/5044; 30.5%) and unsorted (216/756; 28.6%) frozen–thawed sperm, and PCR sex-determination of the embryos confirmed that they were of the predicted sex (n = 16). Delayed return to oestrus (>23 days) was observed in five recipient sows (71.4%). Fetal sacs were observed by transcutaneous ultrasound on Day 18 in one of these sows. Pre-sexed porcine IVP embryos can be successfully produced using sex-sorted frozen–thawed boar sperm, and these embryos are capable of initiating pregnancies when transferred to recipients. However, further refinement of porcine ET protocols are required to enable development to term.