Superovulation treatments and embryo transfer in Angora goats

Abstract

A high incidence of early luteal regression after PMSG [pregnant mare serum gonadotrophin] superovulation was associated with low recovery of embryos from reproductive tracts of Angora goats flushed later than day 5 after onset of estrus. Embryos were successfully recovered (mean 7.9/female) by flushing on days 2-5. Mean ovulation rate after an FSH regimen (16.1 .+-. 0.8) was significantly higher than that after a single injection of PMSG (10.8 .+-. 1.2). Fertilization rate and survival of embryos following transfer to naturally synchronized recipient feral goats did not differ between the 2 gonadotrophin regimens: the mean number of kids born to 47 donors treated with FSH (7.5 .+-. 0.6) was significantly greater than that to 28 donors treated with PMSG (4.8 .+-. 0.6). Irrespective of hormonal treatment, the numbers of embryos recovered and of kids born were correlated with ovulation rate (r = 0.82, P < 0.001 for both). Embryo survival was influenced by ovulation rate in recipients, with 52, 63 and 75% of transferred embryos being carried to term by recipients with 1, 2 and 3 CI [corpus luteum], respectively (P < 0.01). More embryos survived (65%) when 2 embryos were transferred to each recipient than when 1 (51%) or 3 (48%) were transferred. In recipients receiving 2 embryos, survival was significantly improved by transfer of both embryos to the same oviduct (70%) than when 1 was transferred to each oviduct (62%). The percentage survival of embryos was optimal when estrus of recipients was synchronized within .+-. 1 day of estrus in donors.