title: Pregnancy rate in dairy cows treated with progesterone for six days during estrus synchronization with PGF2α.
abstract: The present study evaluated the effect of progesterone supplementation during a double PGF2α injection synchronization protocol on pregnancy per artificial insemination (P/AI) and on the incidence of twin births. Seven hundred and eighty three dairy cows were synchronized with two injections of PGF2α 14 days apart, starting on day 35 postpartum for their first postpartum insemination. Six days before the second PGF2α injection, cows were treated either with a progesterone-releasing intravaginal device (PRID-Delta) and an intramuscular injection of 500mg of progesterone (n=387) or served as control (n=396) and did not receive progesterone treatment. Cows were inseminated 12h after being detected in estrus. Pregnancy was diagnosed 40-45 days later by transrectal palpation. Progesterone administration improved (P<0.05) the percentage of cows detected in estrus in multiparous [(192/255) 75% vs (161/267) 60%], but not in primiparous cows [93/132 (70%) vs 90/129 (70%)]. Progesterone treatment increased P/AI in multiparous [53/192 (28%) vs 27/161 (17%)] but not in primiparous cows [25/93 (27%) vs 29/90 (32%)]. The incidence of twin births tended to be lower (P=0.09) in cows treated with progesterone [1/74 (1%)] than in the control group [4/53 (7%)]. It is concluded that progesterone administration during estrus synchronization with two PGF2α injections in dairy cows improves estral response and increases P/AI in multiparous, but not in primiparous cows, and tended to decrease the incidence of twin births.
authors.affiliation: Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México, Avenida Universidad 3000, México D.F. 04510, Mexico.
authors.forename: M
authors.initials: M
authors.lastname: Orozco
authors.affiliation: Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México, Avenida Universidad 3000, México D.F. 04510, Mexico.
authors.forename: C G
authors.initials: CG
authors.lastname: Gutiérrez
authors.affiliation: División de Ciencias Biológicas y de la Salud, Universidad Autónoma Metropolitana, Unidad Xochimilco, Mexico.
authors.forename: R
authors.initials: R
authors.lastname: López
authors.affiliation: Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México, Avenida Universidad 3000, México D.F. 04510, Mexico.
authors.forename: C
authors.initials: C
authors.lastname: Aguilar
authors.affiliation: Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México, Avenida Universidad 3000, México D.F. 04510, Mexico.
authors.forename: C
authors.initials: C
authors.lastname: Roque
authors.affiliation: Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México, Avenida Universidad 3000, México D.F. 04510, Mexico. Electronic address: jhc@unam.mx.
authors.forename: J
authors.initials: J
authors.lastname: Hernández-Cerón
mesh_terms: D000818:Animals; D002417:Cattle; D003612:Dairying; D015237:Dinoprost / Q000627:therapeutic use*; D004334:Drug Administration Schedule; D004973:Estrus Synchronization / Q000097:blood / Q000379:methods*; D005260:Female; D007315:Insemination, Artificial / Q000379:methods / Q000662:veterinary; D007774:Lactation / Q000502:physiology; D011247:Pregnancy; D018873:Pregnancy Rate; D011374:Progesterone / Q000008:administration & dosage* / Q000097:blood
chemical_list: D011374:Progesterone; D015237:Dinoprost
keywords: Dairy cows; Fertility; Progesterone; Twining rate