The repeatability of superovulatory response and embryo recovery in sheep

Over an 8-year period, a total of 328 Scottish Blackface donor ewes were in volved in a MOET program They were synchronized with fluorogestone acetate sponges and superovulated with ovine FSH. After the onset of estrus, ewes w ere hand-mated and laparoscopic artificial insemination was performed with fresh semen 44-46 h after sponge removal. Embryos were recovered semi-lapar oscopically on either Day 5 or Day 6 after insemination. Of the 328 donor e wes used, 222 ewes were supervoulated only once, while the remaining ewes w ere superovulated either twice (73 ewes), 3 times (26 ewes) or 4 times (7 e wes) at yearly intervals to generate a maximum of 474 records for subsequen t analysis. There was no significant change in either mean ovulation rate o r the mean number of embryos recovered per donor ewe at successive treatmen ts. However, significant (P < 0.05 at least) effects of both year and donor ewe age existed for superovulatory response and number of embryos recovere d, though only the effect of year was significant (P < 0.001) for percentag e embryo recovery. Repeatability was significant (P < 0.05 at least) for bo th superovulatory response (r = 0.55, s e. 0.055) and number of embryos rec overed (r = 0.38, SE 0.074), but not for percentage embryo recovery (r = 0. 04, SE 0.102) (C) 2001 by Elsevier Science Inc.