Multiple factors affecting the efficiency of multiple ovulation and embryo transfer in sheep and goatsAntonio González-Bulnes A H , David T. Baird B , Bruce K. Campbell C , María J. Cocero A , Rosa M. García-García D , E. Keith Inskeep E , Antonio López-Sebastián A , Alan S. McNeilly F , Julián Santiago-Moreno A , Carlos J.H. Souza G and Almudena Veiga-López A
A Departamento de Reproducción Animal, INIA Avda. Puerta de Hierro s/n, 28040-Madrid, Spain.
B Department of Obstetrics and Gynaecology, University of Edinburgh, Little France Crescent, Edinburgh EH16 4SB, UK.
C School of Human Development, University of Nottingham, QMC, Nottingham NG7 2UH, UK.
D Departamento de Ciencia y Tecnología Agroforestal, EUITA-UCLM, Ronda de Calatrava 7, 13071-Ciudad Real, Spain.
E Division of Animal and Veterinary Sciences, College of Agriculture, Forestry and Consumer Sciences, West Virginia University, Morgantown, WV 26506-6108, USA.
F MRC Human Reproductive Sciences Unit, Centre for Reproductive Biology, University of Edinburgh, Little France Crescent, Edinburgh EH16 4SB, UK.
G South Embrapa Cattle & Sheep Research Centre, Rodovia BR 153 km 595, Cx. Postal 242, Vila Industrial – Zona Rural, CEP 96401-970, Bagé, RS, Brazil.
H To whom correspondence should be addressed. email: firstname.lastname@example.org
Reproduction, Fertility and Development 16(4) 421-435 http://dx.doi.org/10.1071/RD04033
Submitted: cfArticle2ecfc1997462761$funcRECEIVEDDATE@499d514d Accepted: 23 March 2004 Published: 6 July 2004
This review offers an overview of the basic characteristics of in vivo embryo technologies, their current status, the main findings and the advances gained in recent years, and the outstanding subjects for increasing their efficiency. The use of superovulation and embryo transfer procedures remains affected by a high variability in the ovulatory response to hormonal treatment and by a low and variable number of transferable embryos and offspring obtained. This variability has been classically identified with both extrinsic (source, purity of gonadotrophins and protocol of administration) and intrinsic factors (breed, age, nutrition and reproductive status), which are reviewed in this paper. However, emerging data indicate that the main causes of variability are related to endocrine and ovarian factors, and so the number of studies and procedures addressing a better understanding and control of these factors may be increased in the future. The accomplishment of this objective, the improvement of procedures for embryo conservation and for the selection and management of recipient females, will allow further development and application of this technology.
Extra keywords: embryo cryopreservation, follicle dynamic, luteal function, superovulation.