Uterine Contractions in the Ewe During Progestagen-Regulated Oestrus

Section: Discussionsupporting

confidence: 90%

Section: Uterine Contraction Study Twenty-ninementioning

confidence: 99%

Fertilization of Ova in Selenium/Vitamin E-Treated Ewes Maintained on Two Planes of Nutrition2

Segerson

Ganapathy

1980

“…A comparison of uterine contractions during estrus in untreated ewes and during the ensuing estrus in progesterone-treated ewes indicated that each of the four progestogen treatments used in the present study reduced the number of contractions moving toward the oviducts and increased the number moving toward the cervix (Hawk and Echternkamp, 1973). Near and soon after the end of estrus the direction of uterine contractions in untreated ewe changes, apparently due to declining estrogen secretion, from predominantly toward the oviducts to predominantly toward the cervix (Hawk, 1975).…”

Section: Discussionmentioning

confidence: 52%

Ovarian and Pituitary Hormones in Blood of Progestogen-Treated Ewes

Echternkamp¹,

Bolt²,

Hawk³

1976

Self Cite

Estradiol (E2), estrone (El), progesterone, LH and prolactin concentrations were determined by radioimmunoassay in blood plasma samples from parous ewes treated with medroxyprogesterone acetate (MAP) or melengestrol acetate (MGA) orally, with MAP by intravaginal sponge, or progesterone by intramuscular injection. Treatment was begun on Day 10 of the estrous cycle and continued for 14 days. Blood samples were collected daily from Day 10 through 13 of the estrous cycle for untreated ewes and from Day 10 through 23 for progestogen-treated ewes, after which the frequency of blood collection was increased to 6-hr intervals until 48 hr after the beginning of estrus.Corpora lutea (CL) regressed, as indicated by a reduction of plasma progesterone concentration, between Day 13 and 15 of the estrous cycle. As soon as the CL regressed, LH (P<.01) and E 2 concentrations increased linearly with time in untreated ewes and in ewes still under treatment with MGA or MAP orally or with progesterone intramuscularly. The increases were not found in ewes treated with MAP

“…Uterine motility is a major contributing factor to sperm transport (Brinsfield and Hawk, 1969;Warren and Hawk, 1971;Hawk and Echternkamp, 1973;Hawk, 1983). Uterine contractions in ewes that have not lambed within the previous 90 d originate near the cervix and move toward the oviducts, whereas most contractions in d-30 postpartum ewes originate near the oviducts and move toward the cervix (Warren and Kiesling, 1982, 1983.…”

Section: Resultsmentioning

confidence: 99%

Conception Rates in Early Postpartum Ewes Bred Naturally or by Intrauterine Insemination

Warren

Kiesling

Akinbami

et al. 1989

Ewes were treated with a medroxyprogesterone acetate (MAP) sponge for 8 d followed, at sponge removal, with 500 IU pregnant mare serum gonadotropin (PMSG) at d 30, 40 or 50 (d 0 = lambing) to induce estrus. Dry and lactating ewes were divided into equal numbers at each postpartum day and bred at estrus. Conception rates and number of accessory sperm were determined by flushing the oviducts 3 d after mating and examining the recovered ova. There was no effect (P greater than .05) of lactational status on conception rates. Conception rates increased (P less than .05) from d 30 (10%) to d 40 (45%) and from d 40 to d 50 (80%). There were fewer (P less than .05) ova with accessory sperm (5/26) in d-30 ewes compared with d-40 (10/27) or d-50 (12/24) ewes. In Exp. 2, ewes were assigned to two groups after receiving PMSG on d 30: 1) mated naturally or 2) inseminated during laparotomy near the uterotubal junction (UTJ). Dry and lactating ewes were divided evenly within each of the two treatments. Oviducts were flushed and ova were examined for cleavage. The conception rate was 60% in ewes that were inseminated in the UTJ vs 10% in ewes mated to rams (P less than .05). Lactational status had no effect on results. In conclusion, conception rates in postpartum ewes treated with MAP sponge and PMSG increased from postpartum d 30 to d 50 with natural breeding, and d-30 conception rates were increased over natural mating by insemination into the uterine horn near the UTJ.