Effect of P.G. 600 on the timing of ovulation in gilts treated with Regu-mate

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dc.contributor.authorHorsley, Brandon Ryanen
dc.contributor.committeechairEstienne, Mark J.en
dc.contributor.committeememberBeal, Wilfred E.en
dc.contributor.committeememberKnight, James W.en
dc.contributor.committeememberHarper, Allen F.en
dc.contributor.departmentAnimal and Poultry Sciencesen
dc.date.accessioned2011-08-06T16:06:25Zen
dc.date.adate2004-09-28en
dc.date.available2011-08-06T16:06:25Zen
dc.date.issued2004-09-14en
dc.date.rdate2004-09-28en
dc.date.sdate2004-09-02en
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
dc.description.degreeMaster of Scienceen
dc.format.mediumETDen
dc.identifier.otheretd-09022004-094041en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-09022004-094041en
dc.identifier.urihttp://hdl.handle.net/10919/10124en
dc.publisherVirginia Techen
dc.relation.haspartFinalThesis3.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectP.G. 600en
dc.subjectRegu-mateen
dc.subjectgilten
dc.subjectestrusen
dc.titleEffect of P.G. 600 on the timing of ovulation in gilts treated with Regu-mateen
dc.typeThesisen
thesis.degree.disciplineAnimal and Poultry Sciencesen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.levelmastersen
thesis.degree.nameMaster of Scienceen
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