Improvement by ergonovine of sperm transport, fertilization and pregnancy rates in ewes in natural or prostaglandin-induced estrus.

Eight experiments were conducted with 451 ewes to test effects of ergonovine, prostaglandin F2 alpha (PGF2 alpha) and phenylephrine on sperm transport and fertility. In most experiments, ewes were mated at estrus and necropsied 2 or 3 h later. Sperm were flushed from the oviducts, uterus and anterior, middle and posterior thirds of the cervix and counted. Various doses of PGF2 alpha or phenylephrine given im at mating caused no significant increase in sperm numbers in any segment of the tract 2 h later. Three different dose levels of ergonovine were given im to ewes in natural estrus 1 h after mating and ewes were necropsied 3 h after mating. Doses of .2 and 1.0 mg were ineffective, but .5 mg increased sperm numbers about 10-fold in the oviducts and uterus. When given im at the time of artificial insemination, .6 mg of ergonovine increased the fertilization rate at 3 d from 5/25 in control ewes to 12/25 (P less than .05). In three experiments with ewes in PGF2 alpha-induced estrus, .6 mg of ergonovine increased sperm numbers in the cervix and uterus at 3 h after mating and in the uterus and oviducts at 23 h, near ovulation. Other ewes were artificially inseminated in the external cervical os and one-half of the ewes were given .6 mg of ergonovine im; ewes not returning to estrus were laparotomized at 22 to 26 d and embryos removed. After insemination during natural estrus with .2 ml of semen, pregnancy rates were 14/25 for control ewes and 15/25 for ergonovine-treated ewes; after insemination during natural estrus with .1 ml of semen, 6/35 and 18/35 (P less than .005); after insemination during PGF2 alpha-induced estrus with .2 ml of semen, 7/60 and 12/60. Fertilization and pregnancy rates combined were 32/145 (22%) for all control ewes and 57/145 (39%) for ergonovine-treated ewes (P less than .005).