title: Reproductive performance of ewes after 5-day treatment with intravaginal inserts containing progesterone in combination with injection of prostaglandin f2alpha.
abstract: Three experiments were conducted with a total of 1579 ewes to examine reproductive performance in response to synchronization of oestrus during the breeding season, using controlled internal drug releasing (CIDR-G) inserts in regimens designed to provide high concentrations of circulating progesterone. In experiment 1, treatment with two CIDR-G inserts for 12 days produced conception rate (79%) and prolificacy (1.9) to first service equivalent to breeding at natural oestrus (56% and 2.0, respectively). Pregnancy rates to two service periods were 90 and 79%, respectively. In experiments 2 and 3, progesterone was delivered by a single CIDR-G insert for 5 days in combination with prostaglandin F2alpha (PGF2alpha; 5 mg i.m., twice, 3 h apart) the day before (experiment 2), or at insert removal (experiment 3). The combined treatments improved rates of synchronization of oestrus (p<0.01) by 23 and 20% points, respectively, and pregnancy rates to the first service period by 19 (p<0.05) and 13 (p<0.01) percentage points, respectively, compared to treatment with PGF2alpha alone. It is concluded that the combination of treatment for 5 days with a CIDR-G insert and two injections of 5 mg PGF2alpha, the day before, or the day of insert removal, were effective treatments to obtain high fertility at synchronized oestrus in ewes during the breeding season.
authors.affiliation: Division of Animal and Veterinary Science, West Virginia University, Morgantown, WV 26506-6108, USA.
authors.forename: A B
authors.initials: AB
authors.lastname: Dixon
authors.forename: M
authors.initials: M
authors.lastname: Knights
authors.forename: J L
authors.initials: JL
authors.lastname: Pate
authors.forename: P E
authors.initials: PE
authors.lastname: Lewis
authors.forename: E K
authors.initials: EK
authors.lastname: Inskeep
mesh_terms: D000282:Administration, Intravaginal; D000818:Animals; D015237:Dinoprost / Q000008:administration & dosage / Q000494:pharmacology*; D004973:Estrus Synchronization / Q000187:drug effects* / Q000502:physiology; D005260:Female; D005298:Fertility / Q000187:drug effects* / Q000502:physiology; D007273:Injections, Intramuscular / Q000662:veterinary; D011247:Pregnancy; D018873:Pregnancy Rate; D011374:Progesterone / Q000008:administration & dosage / Q000494:pharmacology*; D012756:Sheep / Q000502:physiology*; D013997:Time Factors
chemical_list: D011374:Progesterone; D015237:Dinoprost