Abstract
Ewes were injected intramuscularly with prostaglandin F2α-THAM (PG) on day 9 of an estrous cycle. Of 17 ewes given a single dose of 1, 2, 5 or 10 mg of PG, only two were in heat 2 or 3 days later. When ewes were given 10 mg in two 5 mg doses, 3 to 4 hr. apart, or 15 mg in a single dose, 45 of 52 ewes were in heat 2 or 3 days later. During the induced estrus, some ewes were laparotomized and uterine contractions observed. Others were mated naturally and killed either 1 day later for counting sperm cells in the reproductive tract or 3 days later for obtaining ovum fertilization rates and numbers of accessory sperm cells in the zona pellucida. Included for comparison with PG treated ewes were control estrous ewes and ewes in estrus after being treated for 16 days with an intravaginalsponge containing medroxyprogesterone acetate (MAP). In comparison to control ewes, the PG treated ewes had significantly fewer uterine contractions moving toward the oviducts, and fewer sperm cells in the oviducts at 24 hr. after mating. Numbers of sperm cells in other segments of the reproductive tract were not significantly lower in PG treated than in control ewes. Neither the proportion of ova that were fertilized nor the numbers of accessory sperm cells were significantly lower in PG treated than in control ewes. Compared to MAP treated ewes, the PG treated ewes had significantly fewer uterine contractions moving toward the cervix and tended to have more contractions moving toward the oviducts. Fertilization rates or numbers of sperm cells in the zonae pellucidae or in the reproductive tracts did not did not differ significantly. Copyright © 1973. American Society of Animal Science . Copyright 1973 by American Society of Animal Science.