title: Effects of administration of human chorionic gonadotropin or progesterone before maternal recognition of pregnancy on blastocyst development and pregnancy in sheep.
abstract: A series of four experiments with 258 ewes was conducted to determine whether blastocyst size could be altered before normal luteolysis and, if so, how this affected fertility. In Exp. 1 and 2, nonmated and mated ewes, respectively, were treated with hCG (100 IU), progesterone (12 mg), or vehicle on d 11.5 (d 0 = onset of estrus). In Exp. 3 and 4, field trials were conducted to compare the effects of either hCG or progesterone treatment on d 11.5 on subsequent pregnancy rates. In Exp. 1, hCG transiently increased (P < .01) concentrations of progesterone and estradiol in plasma, whereas progesterone treatment increased only plasma progesterone. Neither hCG nor progesterone affected the duration of the estrous cycle. In Exp. 2, d-13 blastocysts were longer (3.5 +/- 1.6 vs .8 +/- .5 cm; Mean +/- SE; P < .05), and concentrations of protein and interferon tau (IFN tau) in uterine flushings were greater (10.7 vs 1.2 micrograms; P < .05) in hCG than in vehicle-treated ewes. Progesterone treatment did not affect blastocyst development. In Exp. 3, pregnancy rates tended to be greater (P < .10) in ewes given hCG than in those given vehicle (44/47; 94% vs 40/48; 83%); however, administration of progesterone in Exp. 4 had no effect on pregnancy rates (P < .14; 41/45; 91% vs 37/46; 80%; control ewes). These results indicate that treatment with hCG on d 11.5 stimulated uterine secretions and conceptus growth sufficiently to influence pregnancy rates.
authors.affiliation: Department of Animal Science, Ohio State University, Columbus 43210.
authors.forename: K P
authors.initials: KP
authors.lastname: Nephew
authors.forename: H
authors.initials: H
authors.lastname: Cárdenas
authors.forename: K E
authors.initials: KE
authors.lastname: McClure
authors.forename: T L
authors.initials: TL
authors.lastname: Ott
authors.forename: F W
authors.initials: FW
authors.lastname: Bazer
authors.forename: W F
authors.initials: WF
authors.lastname: Pope
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000187:drug effects* / Q000502:physiology; D006063:Chorionic Gonadotropin / Q000494:pharmacology*; D003338:Corpus Luteum / Q000187:drug effects; D015237:Dinoprost / Q000378:metabolism; D004958:Estradiol / Q000097:blood; D004971:Estrus / Q000187:drug effects; D005260:Female; D005298:Fertility / Q000187:drug effects*; D011247:Pregnancy; D011374:Progesterone / Q000097:blood / Q000494:pharmacology*; D012756:Sheep / Q000196:embryology / Q000502:physiology*
chemical_list: D006063:Chorionic Gonadotropin; D011374:Progesterone; D004958:Estradiol; D015237:Dinoprost