Effect of estrus expression prior to ovulation synchronization protocols on reproductive efficiency of lactating dairy cow

摘要: Abstract Cosynch-72 (CO-72) is one of the most widely known timed AI (TAI) protocols in cattle. The protocol involves giving GnRH on d-7, PGF 2α day 0, and second 3 concurrent with AI. CO-72 has been adapted as standard reproductive management postpartum (pp) dairy cows several large farms Jordan. This research was conducted to study effect estrus detection presynchronization strategy prior Cosynch efficiency lactating Cows ( n =1220) were injected 30±3 pp observed for signs over experiment. detected before =21) or after =409) injection underwent starting 12 days heat (control group; HCO-72). In contrast, that not randomly assigned into two treatments (NHCO-72; NHOV-CO-72): NHCO-72 treatment a 44±3 pp; while NHOV-CO-72 first without followed by another seven last (day 61±3). showed premature (≤48 h post-PGF ) =184) excluded from study. had higher P