Superovulation and egg transfer in the ewe

102 Prealpes du Sud donor ewes were superovulated by a treatment with vaginal sponges impregnated with 40 mg of FGA. When the sponges were withdrawn at 14 days, follicular maturation was stimulated in these ewes with 12 mg of porcine pituitary extract (pFSH). The recipient ewes were treated i.m. with 500 IU of PMSG. Different batches of pFSH (batch pFSH1/Group A; batch pFSH2: groups B and C) were used; a total of 12 mg was given in 4 injections of 3 mg each (groups A and B) or in decreasing doses of 5, 3, 2, and 1 mg (group C). The embryos were recovered at D6 and transferred after 1 or 5 h of storage in medium 199 or medium B2 (Ménézo, 1976) + 10% FCS at either 37 or 20 degrees C (B only). Surgery was used to recover the embryos and place them (one per uterine horn) in the recipients. pFSH1 induced estrus 24 h after sponge withdrawal in 100% of group A ewes. When the LH level was lower (pFSH2; groups B and C), only 62.5% of the ewes came on heat at 24 h. pFSH2 induced 8.1 corpora lutea per ewe (groups B and C) vs 4.6 in group A (pFSH1) and twofold more viable embryos were recovered in groups B and C than in group A (6.1 vs 2.7). In relation to the number of corpora lutea, 59, 69, 80% of viable embryos were recovered in groups A, B, and C, respectively. There was a positive correlation between the number of corpora lutea and the number of morulae recovered.(ABSTRACT TRUNCATED AT 250 WORDS)