Pre- and post-synchronization methodologies to enhance the efficiency of fixed timed artificial insemination in pharmacologically-controlled breeding systems with Bos indicus-influenced cattle

dc.contributor.advisorWilliams, Gary L.
dc.contributor.committeeMemberBrinsko, Steven P.
dc.contributor.committeeMemberWelsh, Thomas H.
dc.creatorZuluaga Velez, Juan Federico
dc.date.accessioned2007-04-25T20:08:50Z
dc.date.available2007-04-25T20:08:50Z
dc.date.created2006-12
dc.date.issued2007-04-25
dc.description.abstractObjectives were to: 1) Evaluate the effectiveness of presynchronization with GnRH before the CO‐Synch + CIDR protocol with timed AI (TAI) at 66 h in Bos indicus‐influenced cattle; 2) Characterize ovarian events associated with the presynchronization; 3) Evaluate the efficacy of measuring vaginal electrical resistance (VER) to assess follicular maturity at TAI; and 4) Compare serum concentrations of progesterone (P4) in ovariectomized cows bearing new or previously used CIDR devices with or without autoclaving. In Exp. 1 and 2, cattle received either GnRH or saline on day ‐7. The CO‐Synch + CIDR protocol included a CIDR insert and GnRH (GnRH‐1; day 0), removal of CIDR and PGF2α on day 7, and GnRH (GnRH‐2) and TAI 66 h after CIDR removal. In Exp. 1, pregnancy rate of females with BCS ≥ 5 tended to differ (P=0.085) between Presynch (38%) and CO‐Synch + CIDR (54%). In Exp. 2, ovulatory response to GnRH‐1 was greater (P<0.01) in the Presynchronization (58%) than in the CO‐Synch + CIDR (27.1%) group. Emergence of a follicular wave after GnRH‐1 and ovulation rate after GnRH‐2 did not differ between groups. More (P<0.01) females that developed a follicular wave after GnRH‐1 ovulated (82%) after GnRH‐2, compared to those that did not (29%). Mean VER (ohms) was greatest (101.4±0.8) on day 0 and declined (P<0.01) to 95.2±0.8 and 82±0.8, respectively, on days 7 and 10. We observed a low negative but significant relationship (r=0.38; P<0.001) between VER and follicular size on day 0, 7, and 10. VER difference (day 10 minus day 7) did not differ between females with small and large follicles at TAI. Mean concentrations of P4 during the 7‐day insertion period were greater (P<0.03) for new (3.7 ng/ml) and re‐used autoclaved (3.4 ng/ml) than for re‐used disinfected CIDRs (2.8 ng/ml). In summary, Presynch improved ovulation rate after GnRH‐1, but did not improve pregnancy rates compared to CO‐Synch + CIDR. Follicular maturity estimation was not feasible using VER as applied in this study. Autoclaving may be the best option when re‐using CIDR inserts because it creates greater concentrations of P4 during the first 48 h.en
dc.format.digitalOriginborn digitalen
dc.format.extent1111228 bytesen
dc.format.mediumelectronicen
dc.format.mimetypeapplication/pdf
dc.identifier.urihttps://hdl.handle.net/1969.1/4812
dc.language.isoen_US
dc.publisherTexas A&M University
dc.subjectTimed AIen
dc.subjectSynchronizationen
dc.subjectVaginal Electrical Resistanceen
dc.subjectBos indicusen
dc.subjectCIDRen
dc.titlePre- and post-synchronization methodologies to enhance the efficiency of fixed timed artificial insemination in pharmacologically-controlled breeding systems with Bos indicus-influenced cattleen
dc.typeBooken
dc.typeThesisen
dc.type.genreElectronic Thesisen
dc.type.materialtexten
thesis.degree.departmentAnimal Scienceen
thesis.degree.disciplinePhysiology of Reproductionen
thesis.degree.grantorTexas A&M Universityen
thesis.degree.levelMastersen
thesis.degree.nameMaster of Scienceen

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