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dc.contributor.authorHorsley, Brandon Ryanen_US
dc.date.accessioned2011-08-06T16:06:25Z
dc.date.available2011-08-06T16:06:25Z
dc.date.issued2004-09-14en_US
dc.identifier.otheretd-09022004-094041en_US
dc.identifier.urihttp://hdl.handle.net/10919/10124
dc.description.abstractWe previously reported that ovulation rate, but not pregnancy rate or litter size at d 30 post-mating, was enhanced by gonadotropin treatment (P.G. 600; Intervet America Inc., Millsboro, DE) in gilts fed a progestin (Regu-mate; Intervet America Inc.) compared with gilts receiving progestin alone. We hypothesized that P.G. 600 altered the timing of ovulation, therefore mating gilts 12 and 24 h after first detection of estrus, as is common in the swine industry, may not have been the most appropriate breeding regimen. The objective of this study was to determine the effect of P.G. 600 on the timing of ovulation in gilts treated with Regu-mate. Randomly cycling, crossbred gilts (5.5 m of age, 117 kg BW, and 14.7 mm BF) were fed a diet containing Regu-mate to provide 15 mg/d for 18 d. Twenty-four h after Regu-mate withdrawal, gilts received i.m. P.G. 600 (n = 25) or saline (n = 25). Gilts were checked for estrus at 8 h intervals. After first detection of estrus, trans-rectal ultrasonography was performed at 8 h intervals to determine the time of ovulation. Gilts were killed 9 to 11 d after the onset of estrus to determine ovulation rate. All gilts displayed estrus by 7 d after treatment with P.G. 600 or saline. Compared with saline, P.G. 600 increased (P = 0.07) ovulation rate (14.8 + 1.1 vs. 17.5 + 1.0, respectively). The intervals from injection-to-estrus (98.4 + 2.7 vs. 110.9 + 2.7 h; P < 0.01) and injection-to-ovulation (128.6 + 2.8 vs. 141.9 + 3.2 h; P < 0.01) were decreased in gilts treated with P.G. 600 compared with gilts treated with saline. Estrus duration (54.4 + 2.3 vs. 53.7 + 2.5 h; P = 0.83), estrus-to-ovulation (30.2 + 2.0 vs. 31.7 + 2.2 h; P = 0.62) and time of ovulation as a percentage of duration of estrus (55.8 + 2.7 vs. 57.5 + 3.0%; P = 0.67) were similar for the P.G. 600 and saline-injected gilts, respectively. In summary, P.G. 600 advanced the onset of estrus and ovulation following termination of Regu-mate treatment and increased ovulation rate. However, treatment of gilts with P.G. 600 had no effect on the timing of ovulation relative to the onset of estrus.en_US
dc.format.mediumETDen_US
dc.publisherVirginia Techen_US
dc.relation.haspartFinalThesis3.pdfen_US
dc.rightsI hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to Virginia Tech or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report.en_US
dc.subjectP.G. 600en_US
dc.subjectRegu-mateen_US
dc.subjectgilten_US
dc.subjectestrusen_US
dc.titleEffect of P.G. 600 on the timing of ovulation in gilts treated with Regu-mateen_US
dc.typeThesisen_US
dc.contributor.departmentAnimal and Poultry Sciencesen_US
dc.description.degreeMaster of Scienceen_US
thesis.degree.nameMaster of Scienceen_US
thesis.degree.levelmastersen_US
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen_US
thesis.degree.disciplineAnimal and Poultry Sciencesen_US
dc.contributor.committeechairEstienne, Mark Josephen_US
dc.contributor.committeememberBeal, Wilfred E.en_US
dc.contributor.committeememberKnight, James W.en_US
dc.contributor.committeememberHarper, Allen F.en_US
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-09022004-094041en_US
dc.date.sdate2004-09-02en_US
dc.date.rdate2004-09-28
dc.date.adate2004-09-28en_US


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