Proceedings of the 5th International Symposium on EQUINE ...
Proceedings of the 5th International Symposium on EQUINE ...
Proceedings of the 5th International Symposium on EQUINE ...
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Equine Embryo Transfervesicles that were imaged with ultrasound during<str<strong>on</strong>g>the</str<strong>on</strong>g> first pregnancy examinati<strong>on</strong> (5 days aftertransfer) resulted in significantly fewer embry<strong>on</strong>icdeaths than vesicles imaged <strong>on</strong> subsequentexaminati<strong>on</strong>.Reduced uterine t<strong>on</strong>e and quality scores forrecipients were associated with reducedpregnancy rates and tended to be associated withincreased embry<strong>on</strong>ic loss rates. Reduced uterinet<strong>on</strong>e in recipients may indicate a uterineenvir<strong>on</strong>ment that is not maximally compatible forembry<strong>on</strong>ic growth and development. In a previousstudy (McCue et al. 1999), lower circulatingc<strong>on</strong>centrati<strong>on</strong>s <str<strong>on</strong>g>of</str<strong>on</strong>g> progester<strong>on</strong>e appeared to becorrelated with reduced uterine and/or cervicalt<strong>on</strong>e. In <str<strong>on</strong>g>the</str<strong>on</strong>g> present study, <str<strong>on</strong>g>the</str<strong>on</strong>g> incidence <str<strong>on</strong>g>of</str<strong>on</strong>g>embry<strong>on</strong>ic loss was not different for fresh vscooled embryos. Thus, when properly d<strong>on</strong>e,cooling and transporting an embryo is an effectiveway <str<strong>on</strong>g>of</str<strong>on</strong>g> utilising recipients without a decrease inpregnancy rates or an increase in early embry<strong>on</strong>icloss. The results <str<strong>on</strong>g>of</str<strong>on</strong>g> this study suggest thatrecipients should be critically evaluated <strong>on</strong> Day 5after ovulati<strong>on</strong> and used as recipients for embryoswithin 7 days <str<strong>on</strong>g>of</str<strong>on</strong>g> ovulati<strong>on</strong>. The morphology <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g>embryo was predictive <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> potential <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g>embryo to result in a pregnancy or to undergoembryo losses.Embryos that were delayed in developmentwere associated with lower pregnancy rates.Recipient quality and selecti<strong>on</strong> appears to be <str<strong>on</strong>g>the</str<strong>on</strong>g>major factor that could be successfullymanipulated to increase pregnancy rates afterembryo transfer.REFERENCESCarney, N.J., Squires, E.L., Cook, V.M., Seidel, G.E. Jrand Jasko, D.J. (1991) Comparis<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> pregnancyrates from transfer <str<strong>on</strong>g>of</str<strong>on</strong>g> fresh versus cooled,transported equine embryos. Theriogenol. 36, 23-32.Cook, V.M., Squires, E.L., McKinn<strong>on</strong>, A.O., Bailey, J.and L<strong>on</strong>g, P.L. (1989) Pregnancy rates <str<strong>on</strong>g>of</str<strong>on</strong>g> cooledtransported equine embryos. Equine vet. J. Suppl. 8,80-81.Fleury, J.J. and Alvarenga, M.A. (1999) Effects <str<strong>on</strong>g>of</str<strong>on</strong>g>collecti<strong>on</strong> day <strong>on</strong> embryo recovery and pregnancyrates in a n<strong>on</strong>surgical equine embryo transferprogram. Theriogenol. 51, 261.Iuliano, M.F. and Squires, E.L. (1985) Effect <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> age<str<strong>on</strong>g>of</str<strong>on</strong>g> equine embryos and method <str<strong>on</strong>g>of</str<strong>on</strong>g> transfer <strong>on</strong>pregnancy rate. J. anim. Sci. 60, 258-263.McCue, P.M., Vanderwall, D.K., Keith, S.L. and Squires,E.L. (1999) Equine embryo transfer: influence <str<strong>on</strong>g>of</str<strong>on</strong>g>endogenous progester<strong>on</strong>e c<strong>on</strong>centrati<strong>on</strong> in recipients<strong>on</strong> pregnancy outcome. Theriogenol. 51, 267.McKinn<strong>on</strong>, A.O. and Squires, E.L. (1988) Morphologicassessment <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> equine embryo. J. Am. vet. Med.Ass. 192, 401-406.Squires, E.L., Cook, V.M., Jasko, D.J. and Tarr, S.F.(1992) Pregnancy rates after collecti<strong>on</strong> and shipment<str<strong>on</strong>g>of</str<strong>on</strong>g> equine embryos (1988-1991). Proc 38th. Am. Ass.equine Pract. 609-617.Squires, E.L., Imel, K.J., Iuliano, M.F. and Shideler, R.K.(1982) Factors affecting reproductive efficiency inan equine embryo transfer program. J. reprod. Fertil.Suppl. 32, 409-414.Squires, E.L., McCue, P.M. and Vanderwall, D.K. (1999)The current status <str<strong>on</strong>g>of</str<strong>on</strong>g> equine embryo transfer.Theriogenol. 51, 91-104.Squires, E.L. and Seidel, G.E. Jr. (1995)Collecti<strong>on</strong> andTransfer <str<strong>on</strong>g>of</str<strong>on</strong>g> Equine Embryos. Animal Reproducti<strong>on</strong>and Biotechnology Laboratory Bulletin No. 08. FortCollins, CO: Colorado State University.92