Currently most transgenic animals are produced by microinjecting DNA into a pronucleus of in vivo derived embryos. This is an inefficient procedure because of the costs of animals, superovulation and surgery, the low numbers of embryos produced, and their poor viability after injection. Thus, in most well run programmes, only about 10% of injected sheep, pig and cattle embryos result in offspring and only 0.5 to 1% in transgenic offspring. Methods for improving the efficiency are discussed and it is concluded that effective in vitro maturation (IVM), fertilisation (IVF) and culture techniques and alternative methods of gene insertion (particularly through stem cells or sperm - mediated insertion) would make significant contributions to improved results. Ruakura's successful sheep and cattle in vitro oocyte maturation, fertilisation and culture programme and its results are discussed. Recent developments in MOET techniques are discussed and it is concluded that, in the short term, it is possible that more effective multiplication of transgenics could arise from successful IVM/IVF and nuclear transplantation procedures than from significant improvements in current MOET technology. The in vitro produced egg therefore has considerable potential for increasing the efficiency of producing and multiplying transgenics.

KP, McNatty, KM Henderson, JS Fleming, CA Price, and IJ Clarke

Proceedings of the New Zealand Society of Animal Production, Volume 50, , 135-140, 1990
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