Reproduction results and offspring performance after non-surgical embryo transfer in pigs

Factors affecting the production of potential transgenic pigs by DNA microinjection; a six-year retrospective study

“…Surgical procedures for transferring pig embryos have been available for several decades (Ducro-Stevernik et al, 2004). The pregnancy rate of surgical embryo transfer of non-transformed pig embryos averaged about 60% (Ducro-Stevernik et al, 2004).…”

“…Employment of non-surgical methods increased the pregnancy rate, but resulted in a lower litter size (DucroStevernik et al, 2004). Moreover, non-surgical transfer was performed with use of blastocyst stage embryos which require an extra six to seven days of in vitro culture (Ducro-Stevernik et al, 2004). In the case of transformed zygotes, the sooner they are transferred into the recipient oviducts, the greater the chance that the zygotes weakened by microinjection will fi nd proper conditions for further development.…”

Recent advances toward the practical application of embryo transfer in pigs

“…Overall, these studies have reported pregnancy rates of 60% to 90% with 8 to 10 fetuses per pregnant recipient at 25 to 40 days of pregnancy [13,48,50] or farrowing rates and litter sizes of 60% to 80% and 7 to 8 piglets born, respectively [51,52]. These results are higher than those reported after nonsurgical ET into the uterine body (farrowing rates of 33%-40%; litter sizes of 6.7-7.4 piglets) [46,47] but similar to those achieved in the first attempt of the NsDU-ET technique (71.4% farrowing rate and 6.9 piglets/litter) [4]. With NsDU-ET procedural improvements, including the use of aseptic protocols during transfers, an adequate degree of estrous synchrony between recipients and donors and an operator training period (reviewed in [3]), the reproductive performance of recipients has been enhanced, achieving farrowing rates of approximately 80% and litter sizes of approximately 9.5 piglets/litter [5][6][7].…”

“…Among these procedures, the most promising involved the placement of embryos into the uterine body of nonsedated sows [46]. Using this technique under field conditions, 40% farrowing rates and 7.2 piglets/litter were achieved after the transfers [47]. Although these results can be considered as acceptable, improvements were still needed to increase the reproductive performance of the recipients after nonsurgical ET.…”

Embryo Transfer andin vitroFertilization

“…It was recently reported that 71 percent of sows farrowed an average of 6.9 piglets following nonsurgical transfer into one uterine horn using a catheter specifi cally designed for the procedure (Martinez et al, 2004). In a commercial application of nonsurgical transfers averaging 28 blastocysts per gilt recipient, 41 percent farrowed an average of 7.2 piglets, compared to 12.8 percent for controls (Ducro-Steverink et al, 2004). In another recent report, success of nonsurgical transfer in gilts was directly related to the number of the estrus, with cervical passage not possible unless gilts had exhibited three or more estrous cycles .…”