Evaluating the effectiveness of using the controlled internal drug release (CIDR) insert for synchronization of estrus and post-insemination progesterone therapy to improve reproductive performance of dairy cattle
Fain, Jillian L.
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Study 1 combined the CIDR insert for ovulation synchronization and TAI. Animals received 50 µg GnRH (-9 d), CIDR (1.38 g progesterone) (-9 d), 25 mg PGF (-3 d), 1 mg ECP 2 .(-2 d), -CIDR (-2 d), GnRH (d 0), and TAI (0 d), (OverSynch; n=20) or CIDR (-9 d), PGF2 . (-3 d), -CIDR (-2 d), and TAI (0 d) (Control; n=20). Pregnancy rates did not differ (P > 0.05); however, estrus activity was increased with OverSynch (P < 0.05). Study 2 utilized the CIDR to decrease embryonic loss and for reuse in resynchronization post AI. Supplementation had no effect on pregnancy rates, regardless of season (P > 0.05). Progesterone concentrations post AI tend to be higher in heifers than in cows (P = 0.0651) and in dairy versus beef heifers (P < 0.05). Overall, d 21 progesterone concentrations is positively correlated with d 35 pregnant diagnosis (P = 0.004).