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Abstract

Superovulation treatments and embryo transfer in Angora goats.

Abstract

A high incidence of early luteal regression after superovulation using 750-1250 IU PMSG was associated with low recovery of embryos from reproductive tracts of Angora goats flushed later than day 5 after the onset of oestrus. Embryos were successfully recovered (mean 7.9 per female ) by flushing on days 2-5. The mean ovulation rate (16.1 plus or minus 0.8) after an FSH regimen (twice daily injection over 4 days; total dose 18 mg FSH equivalent) was significantly higher than that after a single injection of PMSG (10.8 plus or minus 1.2). Fertilization rate and survival of embryos following transfer to naturally synchronized recipient feral goats did not differ between the 2 gonadotropin regimens: the mean number of kids born to 47 donors treated with FSH (7.5 plus or minus 0.6) was significantly greater than that to 28 donors treated with PMSG (4.8 plus or minus 0.6). Irrespective of hormone treatment, the numbers of embryos recovered and of kids born were correlated with ovulation rate (each, 0.82, P<0.001). 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 corpora lutea (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 recipients were synchronized within plus or minus 1 day of donors.