title: Luteal function, estrous response, and pregnancy rate after treatment with Norgestomet and various dosages of estradiol valerate in suckled cows.
abstract: Two experiments were conducted to determine whether dosage of estradiol valerate (EV) or day of estrous cycle when treatment was administered affected response to Syncro-Mate-B (SMB). Suckled beef cows received a 6-mg Norgestomet (NOR) ear implant (in situ 9 d) and a 3-mg NOR i.m. injection. In Exp. 1, 74 cows received NOR treatments concurrently with either 5 or 6 mg of EV administered i.m. on either d 1, 3, or 5 of an estrous cycle (estrus = d 1). In Exp. 2, 169 cows received NOR treatments concurrently with either 5, 7, or 9 mg of EV administered i.m. on either d 3 or 9 of an estrous cycle. In Exp. 1, 67, 50 and 92%, respectively, of cows receiving 5 mg of EV on d 1, 3, or 5 had functional corpora lutea (CL) at implant removal, whereas 42, 75, and 77%, respectively, of cows receiving 6 mg of EV had functional CL at implant removal (dosage P greater than .10; day P less than .05). Synchronized estrous responses were 50, 33, and 23%, respectively, when cows received 5 mg of EV on d 1, 3, or 5, and 67, 33, and 38%, respectively, when cows received 6 mg of EV (dosage P greater than .10; day P less than .05). First-service pregnancy rate was decreased (P less than .05) in cows treated on d 5 (33%) compared with cows treated on d 1 (63%), but dosage of EV had no effect on pregnancy rate.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Anim. Dairy and Vet. Sci. Dept., Clemson University, SC 29634-0361.
authors.forename: S L
authors.initials: SL
authors.lastname: Pratt
authors.forename: J C
authors.initials: JC
authors.lastname: Spitzer
authors.forename: G L
authors.initials: GL
authors.lastname: Burns
authors.forename: B B
authors.initials: BB
authors.lastname: Plyler
mesh_terms: D000818:Animals; D002417:Cattle / Q000502:physiology*; D003338:Corpus Luteum / Q000187:drug effects* / Q000502:physiology; D004343:Drug Implants; D004958:Estradiol / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D004966:Estrogens, Conjugated (USP) / Q000494:pharmacology; D004971:Estrus / Q000187:drug effects*; D004973:Estrus Synchronization / Q000187:drug effects; D005260:Female; D005298:Fertility / Q000187:drug effects; D007273:Injections, Intramuscular; D007315:Insemination, Artificial / Q000662:veterinary; D011247:Pregnancy; D011282:Pregnenediones / Q000008:administration & dosage / Q000494:pharmacology*; D011374:Progesterone / Q000097:blood; D045167:Progesterone Congeners / Q000494:pharmacology; D011897:Random Allocation
chemical_list: D004343:Drug Implants; D004966:Estrogens, Conjugated (USP); D011282:Pregnenediones; D045167:Progesterone Congeners; C100284:norgestomet; D011374:Progesterone; D004958:Estradiol