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Published online by Cambridge University Press: 24 November 2017
Over the course of the last 40 years or so increasingly reliable procedures have been developed for multiple ovulation, embryo recovery and embryo transfer, initially for cattle (see review of Woolliams and Wilmut, 1989) and, more recently, for small ruminants (McKelvey and Robinson, 1986). During this time a number of applications have been proposed or practised. These include uses in (i) within-breed genetic improvement programmes, (ii) the import and export of genetic material (offering potential advantages in economy, animal welfare and disease control), (iii) accelerating breed substitution by multiplication of newly introduced breeds and (iv) conservation of genetic material (by freezing embryos) from valuable individual animals, or from rare or endangered breeds or species. Additionally, there are several new ‘reproductive’ procedures available or being developed for use in animal production (eg. in vitro fertilisation, embryo sexing, cloning, gene transfer) which hinge on the use of embryo transfer. These are discussed in detail by Woolliams and Wilmut (1989) and in the following two papers. The aim of this paper is to examine the first of the applications listed above - the use of multiple ovulation and embryo transfer (MOET) in within-breed genetic improvement programmes.