Induced Estrus in Anestrous Ewes by Use of Progestogens and Follicle Stimulating Hormone

Abstract

A high incidence of estrus (91.3%) and ovulation (98.4%) was successfully induced in anestrous ewes receiving progesterone pretreatment for 9 to 19 days and a single injection of 20 mg. to 50 mg. FSH. Significantly greater variation (P <0.01) in ovulation rate occurred when FSH was administered 24 hours instead of 48 hours after the last progesterone injection. Oral administration of 6 methyl-17-acetoxy-progesterone for 12 days successfully replaced progesterone injections as the pretreatment for inducing estrus. Eighty percent of the anestrous ewes receiving 10 mg., 30 mg. and 60 mg. 6-methyl-17-acetoxyprogesterone once daily for 12 days and a single 25 mg. FSH injection exhibited estrus within 48 hours. Injection of 25 mg. FSH without pretreatment induced estrus in 17.6% of the 17 treated ewes. A 12-day interval between the 125 mg. 17-hydroxyprogesterone-17-caproate injection and the 25-mg. FSH injection resulted in estrus induction in 3 of the 4 ewes treated. Intervals of 8 and 10 days between injections were less satisfactory. Copyright © . .