Synchronization rate, size of the ovulatory follicle, and pregnancy rate after synchronization of ovulation beginning on different days of the estrous cycle in lactating dairy cows

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dc.contributor.authorVasconcelos, J L M
dc.contributor.authorSilcox, R. W.
dc.contributor.authorRosa, G J M
dc.contributor.authorPursley, J R
dc.contributor.authorWiltbank, M. C.
dc.contributor.institutionUniv Wisconsin
dc.contributor.institutionUniversidade Estadual Paulista (Unesp)
dc.contributor.institutionBrigham Young Univ
dc.contributor.institutionMichigan State University
dc.date.accessioned2014-05-20T15:25:10Z
dc.date.available2014-05-20T15:25:10Z
dc.date.issued1999-10-15
dc.description.abstractRecently a protocol was developed that precisely synchronizes the time of ovulation in lactating dairy cows (Ovsynch; GnRH-7d-PGF(2 alpha)-2d-GnRH). We evaluated whether initiation of Ovsynch on different days of the estrous cycle altered the effectiveness of this protocol. The percentage of cows (n=156) ovulating to the first GnRH was 64% and varied (P<0.01) by stage of estrous cycle. Treatment with PGF(2 alpha) was effective, with 93% of cows having low progesterone at second GnRH. The overall percentage of cows that ovulated after second GnRH (synchronization rate) was 87% and varied by response to first GnRH (92% if ovulation to first GnRH vs 79% if no ovulation; P<0.05). There were 6% of cows that ovulated before the second injection of GnRH and 7% with no detectable ovulation by 48 h after second GnRH. Maximal diameter of the ovulatory follicle varied by stage of estrous cycle, with cows in which Ovsynch was initiated at midcycle having the smallest follicles. In addition, milk production and serum progesterone concentration on the day of PGF(2 alpha) affected (P<0.05) size of the ovulatory follicle. Using these results we analyzed pregnancy rate at Days 28 and 98 after Al for cows (n=404) in which Ovsynch was initiated on known days of the estrous cycle. Pregnancy rate was lower for cows expected to ovulate larger follicles than those expected to ovulate smaller follicles (P<0.05; 32 vs 42%). Thus, although overall synchronization rate with Ovsynch was above, 85%, there were clear differences in response according to day of protocol initiation. Cows in which Ovsynch was initiated near midcycle had smaller ovulatory follicles and greater pregnancy rates. (C) 1999 by Elsevier B.V.en
dc.description.affiliationUniv Wisconsin, Dept Dairy Sci, Madison, WI 53706 USA
dc.description.affiliationUNESP, Fac Med Vet & Zootecn, Botucatu, SP, Brazil
dc.description.affiliationBrigham Young Univ, Dept Anim Sci, Provo, UT 84602 USA
dc.description.affiliationUNESP, Inst Biociencias, Botucatu, SP, Brazil
dc.description.affiliationMichigan State Univ, Dept Anim Sci, E Lansing, MI 48824 USA
dc.description.affiliationUnespUNESP, Fac Med Vet & Zootecn, Botucatu, SP, Brazil
dc.description.affiliationUnespUNESP, Inst Biociencias, Botucatu, SP, Brazil
dc.format.extent1067-1078
dc.identifierhttp://dx.doi.org/10.1016/S0093-691X(99)00195-8
dc.identifier.citationTheriogenology. New York: Elsevier B.V., v. 52, n. 6, p. 1067-1078, 1999.
dc.identifier.doi10.1016/S0093-691X(99)00195-8
dc.identifier.issn0093-691X
dc.identifier.urihttp://hdl.handle.net/11449/35630
dc.identifier.wosWOS:000083806400011
dc.language.isoeng
dc.publisherElsevier B.V.
dc.relation.ispartofTheriogenology
dc.relation.ispartofjcr2.136
dc.rights.accessRightsAcesso restrito
dc.sourceWeb of Science
dc.subjectsynchronizationpt
dc.subjectGnRHpt
dc.subjectPGF(2 alpha)pt
dc.subjectpregnancy ratept
dc.subjectdairy cowspt
dc.titleSynchronization rate, size of the ovulatory follicle, and pregnancy rate after synchronization of ovulation beginning on different days of the estrous cycle in lactating dairy cowsen
dc.typeArtigo
dcterms.licensehttp://www.elsevier.com/about/open-access/open-access-policies/article-posting-policy
dcterms.rightsHolderElsevier B.V.
unesp.author.orcid0000-0001-8188-0991[5]
unesp.author.orcid0000-0001-9172-6461[3]
unesp.author.orcid0000-0001-6324-3614[1]

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