Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10893078 | Theriogenology | 2009 | 6 Pages |
Abstract
The objective was to compare reproductive performance of Angus-cross beef cows synchronized with GnRH, a progesterone-based intravaginal insert (Controlled Internal Drug Release, CIDR) for 5-d, and one dose of either dinoprost (PGF) or cloprostenol (CLP, a PGF analogue) or two doses of PGF on the day of CIDR withdrawal. All cows (N = 830) at six locations received 100 μg of GnRH and a CIDR on Day 0. Within farm, cows were randomly allocated to receive 25 mg of PGF at the time of CIDR insert removal on Day 5 (1 Ã PGF; N = 277), two 25 mg doses of PGF, the first given on Day 5 at the time of CIDR removal and the second 7 h later (2 Ã PGF; N = 282), or 500 μg of CLP at the time of CIDR removal on Day 5 (1 Ã CLP; N = 271). All cows were given 100 μg of GnRH on Day 8 (72 h after CIDR removal) and concurrently inseminated (5-d CO-Synch + CIDR). Cows were fitted with a pressure-sensitive estrus detection device at the time of CIDR withdrawal. Timed-AI pregnancy rates were greater (P < 0.0001) in the 2 Ã PGF (69.0%) than the 1 Ã PGF (52.0%) and 1 Ã CLP (54.3%) treatments. However, breeding-season pregnancy rates were not different among treatments (87.0% for 1 Ã PGF, 92.9% for 2 Ã PGF and 87.5% for 1 Ã CLP; P > 0.1). In conclusion, cows that received two doses of PGF on the day of CIDR removal in a 5-d CO-Synch + CIDR synchronization protocol had excellent timed-AI pregnancy rates that were greater than in cows receiving a single treatment with either PGF or CLP.
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Authors
R. Kasimanickam, M.L. Day, J.S. Rudolph, J.B. Hall, W.D. Whittier,