Applying variations of the Ovsynch protocol at the middle of the estrus cycle on reproductive performance of lactating dairy cows during summer and winter

作者：Alnimer M A^*; Tabbaa M J; Ababneh M M; Lubbadeh W F

来源：Theriogenology, 2009, 72(5): 731-740.

DOI：10.1016/j.theriogenology.2009.05.006

• Cosynch
• Dairy cow
• Ovsynch
• Pregnancy rate
• Season

Two modifications of the Ovsynch protocol, GnRH TAI after PGF(2 alpha) 48 h (CO-48) or 72 It (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.

• 出版日期2009-9-15