Development of embryotransfer methods in swine

Porcine embryo transfers have been performed for approximately 50 years, and surgical methods have been proven to be reliable for the transfer of embryos. On the 4(th) or 5(th) day after twelve to twenty embryos in stages of a few cells of morulae and blastocysts are moved into an isolated uterus horn or oviduct. Pregnancy rates and litter sizes after conventional surgery were 12% to 100% and 6 to 8 piglets, respectively. Its efficacy is dependent on age of recipients, the stage of embryo development, numbers of yellow bodies on the ovaries of the recipients, numbers and place in the uterus horn where embryos were transferred. Less invasive than surgical methods is endoscopic embryo transfer. Lately, the mini-laparotomy for embryo transfer has been described. This method consists of a midventral incision-of 4cm enabling the surgeon to grasp a uterus horn with two ringers and exteriorize it. The results are comparable to conventional methods. The cervix is a barrier for transferring porcine embryos non-surgically. Different instruments for nonsurgical embryo transfer in swine were used. Most of them were modified versions of artificial spirette catheters and special instruments. The obtained results differed: from 30 to 60% of pregnancies and 1.8 to 6.2 live born piglets. The modified flexible catheters originally developed for deep intrauterine insemination in pigs were used to insert swine embryos. The time required to successfully complete the procedure of embryo transfer depends on the type of female, and lasts about 2.5 minutes. The farrowing rate was 70.8% and 6.9 piglets were born on average. This new method offers new possibilities for the nonsurgical transfer of embryos in swine.