Journal article
Effect of timing of prostaglandin administration, controlled internal drug release removal and gonadotropin releasing hormone administration on pregnancy rate in fixed-time AI protocols in crossbred Angus cows
Theriogenology, Vol.66(2), pp.166-172
2006
Handle:
https://hdl.handle.net/2376/105258
PMID: 16310840
Abstract
Two experiments were conducted to investigate the effects of timing of prostaglandin F2
α (PGF2
α) administration, controlled internal drug release device (CIDR) removal and second gonodotropin releasing hormone (GnRH) administration on the pregnancy outcome in CIDR-based synchronization protocols. In Experiment 1, suckled Angus crossbred beef cows (
n
=
580) were given 100
μg of GnRH
+
a CIDR on Day 0. Cows in Group 1 (modified Ovsynch-P) received 25
mg of dinoprost (PGF2
α) and CIDR device removal on Day 8 (AM), 100
μg of GnRH 36
h later on Day 9 (p.m.), and fixed-time AI (FTAI) 16
h later on Day 10 (47.5
±
1.1
h after PGF2
α). Cows in Group 2 (Ovsynch-P) received 25
mg of PGF2
α and CIDR device removal on Day 7 (p.m.), 100
μg of GnRH 48
h later on Day 9 and FTAI 16
h later on Day 10 (66.6
±
1.2
h after PGF2
α). Pregnancy rates were 56.5% (170/301) for Group 1 and 55.6% (155/279) for Group 2, respectively (
P
=
0.47). In Experiment 2, beef cows (
n
=
734) were synchronized with 100
μg of GnRH
+
CIDR on Day 0, 25
mg of PGF2
α and CIDR device removal on Day 7 and either 100
μg of GnRH 48
h later on Day 9 (Ovsynch-P) and FTAI 16
h later on Day 10 (64.9
±
3.3
h from PGF2
α) or 100
μg of GnRH on Day 10 (CO-Synch-P) at the time of AI (63.2
±
4.2
h from PGF2
α). Pregnancy rates were 48.8% (180/369) for Ovsynch-P and 44.7% (163/365) for CO-synch-P groups, respectively (
P
=
0.11). In both experiments, there was a location
×
treatment interaction (
P
<
0.05); pregnancy rates between locations were different (
P
<
0.05) in the Ovsynch-P group. In conclusion, in a CIDR-based Ovsynch synchronization protocol, delaying administration of prostaglandin and CIDR removal by 12
h, or timing of the second GnRH by 16
h, did not affect pregnancy rates to FTAI. Therefore, there may be an opportunity to make changes in synchronization protocols with out adversely affecting FTAI pregnancy rates.
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Details
- Title
- Effect of timing of prostaglandin administration, controlled internal drug release removal and gonadotropin releasing hormone administration on pregnancy rate in fixed-time AI protocols in crossbred Angus cows
- Creators
- R Kasimanickam - Department of Large Animal Clinical Sciences, Virginia-Maryland Regional College of Veterinary Medicine, Blacksburg, VA 24061, USAJ.C Collins - Department of Large Animal Clinical Sciences, Virginia-Maryland Regional College of Veterinary Medicine, Blacksburg, VA 24061, USAJ Wuenschell - Department of Animal and Poultry Sciences, College of Agricultural and Life Science, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USAJ.C Currin - Department of Large Animal Clinical Sciences, Virginia-Maryland Regional College of Veterinary Medicine, Blacksburg, VA 24061, USAJ.B Hall - Department of Animal and Poultry Sciences, College of Agricultural and Life Science, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USAD.W Whittier - Department of Large Animal Clinical Sciences, Virginia-Maryland Regional College of Veterinary Medicine, Blacksburg, VA 24061, USA
- Publication Details
- Theriogenology, Vol.66(2), pp.166-172
- Academic Unit
- Veterinary Clinical Sciences, Department of
- Publisher
- Elsevier Inc
- Identifiers
- 99900546890901842
- Language
- English
- Resource Type
- Journal article