Journal article
Effect of timing of second prostaglandin F 2α administration in a 5-day, progesterone-based CO-Synch protocol on AI pregnancy rates in beef cows
Theriogenology, Vol.74(6), pp.1002-1009
2010
Handle:
https://hdl.handle.net/2376/116385
PMID: 20580078
Abstract
The objective was to compare the timed AI pregnancy rate of Angus-cross beef cows synchronized with a 5-d CO-Synch + CIDR (a progesterone-releasing intravaginal insert) protocol and given two doses of PGF
2α (PGF), with the first dose in conjunction with CIDR withdrawal on Day 5, and the second dose given either early or late relative to the first dose. All cows (N = 1782) at 16 locations received 100 μg of GnRH + CIDR on Day 0. Cows received 25 mg of PGF concurrent with removal of the CIDR on Day 5, and were randomly allocated within locations to receive a second PGF either early (N = 881; from 0.5 to 3.9 h) or late (N = 901; from 4.5 to 8.15 h) relative to the first PGF treatment. On Day 8 (72 h after CIDR removal), all cows were inseminated and concurrently given 100 μg of GnRH. Cows were fitted with a pressure-sensitive mount detection device (Kamar) at CIDR removal. Cows were observed twice daily through Day 7 and at the time of AI on Day 8 for estrus and Kamar status (estrus – red, partial and lost Kamar versus no estrus – white Kamar) was recorded. Accounting for location, season, AI sire, cow observed in estrus or not at or before timed AI, and treatment by cows observed in estrus interaction, timed AI pregnancy rates were greater for the late (6.45 ± 0.03 h) than the early (2.25 ± 0.05 h) interval, 57.2 vs. 52.7%, respectively (P < 0.05). In conclusion, cows that received the second PGF late after the first PGF on the day of CIDR removal in a 5 d CO-Synch + CIDR synchronization protocol had significantly higher timed AI pregnancy rates than those receiving the second PGF early after the first PGF.
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Details
- Title
- Effect of timing of second prostaglandin F 2α administration in a 5-day, progesterone-based CO-Synch protocol on AI pregnancy rates in beef cows
- Creators
- W.D Whittier - Department of Large Animal Clinical Sciences, Virginia Maryland Regional College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061R.K Kasimanickam - Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Washington State University, Pullman, WA 99164J.F Currin - Department of Large Animal Clinical Sciences, Virginia Maryland Regional College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061H.H Schramm - Department of Large Animal Clinical Sciences, Virginia Maryland Regional College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061M Vlcek - Department of Large Animal Clinical Sciences, Virginia Maryland Regional College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061
- Publication Details
- Theriogenology, Vol.74(6), pp.1002-1009
- Academic Unit
- Veterinary Clinical Sciences, Department of
- Publisher
- Elsevier Inc
- Identifiers
- 99900547508801842
- Language
- English
- Resource Type
- Journal article