UNSATISFACTORY RESULTS WITH THE TRANSFER OF EMBRYOS FROM GILTS SUPEROVULATED WITH PMSG AND HCG

Prepuberal gilts received an intramuscular injection of either a single dose of PG 600 (400 IU pregnant mare serum and 200 IU human chorionic gonadotropin) (n = 21), twice (n = 18) or three times (n = 24) that amount. This was followed by 500 IU hCG 56 h later. Most of the gilts were inseminated 36 h following treatment. Of the 63 donors, 58 responded to treatment with, on average, 20.8, 36.7 and 55.8 ovulations, and embryo/ova recovery rates of 80, 76.3 and 53.8% for the three respective dosages. Within 2 to 4 h after collection, synchronized gilts received 16 to 18 morphologically normal embryos transferred into the oviduct. The recipients were slaughtered at 28 to 32 d after embryo transfer, and 10 of 11, 6 of 11 and 9 of 13 gilts in the three treatment groups were found to be pregnant; the average number of viable conceptuses was 6.6, 6.1 and 6.6. There was a lower embryo recovery and pregnancy rate associated with the administration of increasing dosages of PMSG and hCG; thus this regimen is not recommended.