title: Presynchronization with Double-Ovsynch improves fertility at first postpartum artificial insemination in lactating dairy cows.
abstract: The objective of this study was to compare circulating progesterone (P4) profiles and pregnancies per AI (P/AI) in lactating dairy cows bred by timed artificial insemination (TAI) following Ovsynch-56 after 2 different presynchronization protocols: Double-Ovsynch (DO) or Presynch-Ovsynch (PS). Our main hypothesis was that DO would increase fertility in primiparous cows, but not in multiparous cows. Within each herd (n=3), lactating dairy cows (n=1,687; 778 primiparous, 909 multiparous) were randomly assigned to DO [n=837; GnRH-7d-PGF(2α)-3d-GnRH-7d-Ovsynch-56 (GnRH-7d-PGF(2α)-56h-GnRH-16hTAI)] or PS (n=850; PGF(2α)-14d-PGF(2α)-12d-Ovsynch-56). In 1 herd, concentrations of P4 were determined at the first GnRH (GnRH1) of Ovsynch-56 and at d 11 after TAI (n=739). In all herds, pregnancy was diagnosed by palpation per rectum at 39 d. In 1 herd, the incidence of late embryo loss was determined at 74d, and data were available on P/AI at the subsequent second service. Presynchronization with DO reduced the percentage of animals with low P4 concentrations (<0.50 ng/mL) at GnRH1 of Ovsynch-56 (5.4 vs. 25.3%, DO vs. PS). A lesser percentage of both primiparous and multiparous cows treated with DO had low P4 concentrations at GnRH1 of Ovsynch-56 (3.3 vs. 19.7%, DO vs. PS primiparous; and 8.8 vs. 31.9%, DO vs. PS multiparous). Presynchronization with DO improved P/AI at the first postpartum service (46.3 vs. 38.2%, DO vs. PS). Statistically, a fertility improvement could be detected for primiparous cows treated with DO (52.5 vs. 42.3%, DO vs. PS, primiparous), but only a tendency could be detected in multiparous cows (40.3 vs. 34.3%, DO vs. PS, multiparous), consistent with our original hypothesis. Presynchronization treatment had no effect on the incidence of late embryo loss after first service (8.5 vs. 5.5%, DO vs. PS). A lower body condition score increased the percentage of cows with low P4 at GnRH1 of Ovsynch-56 and reduced fertility to the TAI. In addition, P4 concentration at d 11 after TAI was reduced by DO. The method of presynchronization at first service had no effect on P/AI at the subsequent second service (34.7 vs. 36.5%, DO vs. PS). Thus, presynchronization with DO induced cyclicity in most anovular cows and improved fertility compared with PS, suggesting that DO could be a useful reproductive management protocol for synchronizing first service in commercial dairy herds.
authors.affiliation: Teagasc, Animal and Grassland Research and Innovation Centre, Moorepark, Fermoy, Co. Cork, Ireland.
authors.forename: M M
authors.initials: MM
authors.lastname: Herlihy
authors.forename: J O
authors.initials: JO
authors.lastname: Giordano
authors.forename: A H
authors.initials: AH
authors.lastname: Souza
authors.forename: H
authors.initials: H
authors.lastname: Ayres
authors.forename: R M
authors.initials: RM
authors.lastname: Ferreira
authors.forename: A
authors.initials: A
authors.lastname: Keskin
authors.forename: A B
authors.initials: AB
authors.lastname: Nascimento
authors.forename: J N
authors.initials: JN
authors.lastname: Guenther
authors.forename: J M
authors.initials: JM
authors.lastname: Gaska
authors.forename: S J
authors.initials: SJ
authors.lastname: Kacuba
authors.forename: M A
authors.initials: MA
authors.lastname: Crowe
authors.forename: S T
authors.initials: ST
authors.lastname: Butler
authors.forename: M C
authors.initials: MC
authors.lastname: Wiltbank
mesh_terms: D000818:Animals; D002417:Cattle; D004973:Estrus Synchronization / Q000379:methods* / Q000502:physiology; D005260:Female; D005298:Fertility / Q000502:physiology; D007315:Insemination, Artificial / Q000379:methods / Q000502:physiology / Q000662:veterinary*; D007774:Lactation / Q000502:physiology; D010053:Ovary / Q000000981:diagnostic imaging; D010298:Parity / Q000187:drug effects / Q000502:physiology; D011247:Pregnancy; D011374:Progesterone / Q000097:blood / Q000502:physiology; D014463:Ultrasonography
chemical_list: D011374:Progesterone