Limitationof multi-ovulations in Karakul ewes after the use of pregnant mare serum gonadotrofien(PMSG)

One hundred and eight mature Karakul ewes were randomly divided into 9 equal groups. Intravaginal sponges impregnated with 60 mg medroxy-actate progesterone (MAP, Upjohn) were inserted in each ewe and left in situ for 13 days. PMSG (Upjohn) was injected in the different groups as follows: Group 1. 500 IU. Intramuscularly 24hr before sponge withdrawal Group 2. As Group 1, but the hormone was injected subcutaneously. Group 3. As Group 1, but the hormone was injected at sponge withdrawal. Group 4. As Group 1, but the hormone was injected subcutaneously at sponge withdrawal. Groups 5, 6, 7 and 8 were identically treated to the abovementioned groups, but 300 IU. PMSG were used. Group 9 served as the control, with no PMSG administered. All the ewes were tested for oestrus at two hourly intervals commencing 12 hr after sponge withdrawal until all the ewes were in oestrus. Laparotomies were performed 8 days after sponge withdrawal to determine the number of ovulations in each ewe. The time from sponge withdrawal to the commencement of oestrus was less and the number of ovulations per ewe greater following the earlier administration of the larger dose of PMSG. Intrasmuscular as opposed to subcutaneous injection of the larger dose of PMSG also significantly increased ovulation rate, but method on injection had no effect at the lower level.