title: Applying variations of the Ovsynch protocol at the middle of the estrus cycle on reproductive performance of lactating dairy cows during summer and winter.
abstract: Two modifications of the Ovsynch protocol, GnRH+TAI after PGF(2 alpha) 48 h (CO-48) or 72 h (CO-72), were compared with the original protocol (OVS: GnRH-7 d-PGF(2 alpha)-2 d-GnRH-16 h-TAI) to study their effects on reproductive performance in 785 lactating dairy cows (Holstein Friesian, Bos Taurus). Results showed that more cows (P<0.001) returned to estrus within a week after TAI with CO-48 treatment compared with that in OVS and CO-72 treatments. Pregnancy rates were greater (P<0.001) for the CO-72 cows than those for both OVS and CO-48 treatments and for primiparous cows compared with multiparous cows. Moreover, pregnancy rates were lower in summer compared with those in winter. Pregnancy losses for cows in both CO-48 and CO-72 were greater (P<0.05) than that for cows in OVS treatment. Pregnancy losses were greater in summer (P<0.001) than in winter and for multiparous cows (P<0.001) than for primiparous cows. In conclusion, primiparous and winter-bred cows had greater pregnancy rates and fewer pregnancy losses than those of multiparous cows and summer-bred cows, respectively. Because of the presence of significant treatment, parity, and season interactions, TAI with ovulation synchronization protocols should be tailored according to the season and parity. CO-72 is recommended for primiparous cows but not for multiparous cows, and CO-48 is not recommended for synchronization. Furthermore, cows that exhibited estrus at any time were inseminated to improve pregnancy rates in ovulation synchronization protocols.
authors: Department of Animal Production, Faculty of Agriculture, University of Jordan, Amman, Jordan. amufeed@ju.edu.jo
authors: M A
authors: MA
authors: Alnimer
authors: M J
authors: MJ
authors: Tabbaa
authors: M M
authors: MM
authors: Ababneh
authors: W F
authors: WF
authors: Lubbadeh
mesh_terms: D000818:Animals; D002417:Cattle / Q000502:physiology; D003612:Dairying; D015237:Dinoprost / Q000008:administration & dosage / Q000494:pharmacology; D004334:Drug Administration Schedule; D004526:Efficiency / Q000187:drug effects / Q000502:physiology; D030762:Estrous Cycle / Q000187:drug effects / Q000502:physiology*; D004972:Estrus Detection / Q000379:methods; D004973:Estrus Synchronization / Q000379:methods*; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000008:administration & dosage; D007774:Lactation / Q000502:physiology*; D010298:Parity; D011247:Pregnancy; D018873:Pregnancy Rate; D012098:Reproduction / Q000187:drug effects / Q000502:physiology*; D012621:Seasons
chemical_list: D007987:Gonadotropin-Releasing Hormone; D015237:Dinoprost