Transgenesis to improve animal production

Abstract

The improvement of animal production by transgenesis is expected to be complementary to other breeding techniques including genetic selection (by conventional methods and using genetic markers), feed optimization, control of reproduction and struggle against diseases. It may introduce new and efficient methods to solve various problems as is already the case for plants. The success of transgenesis for animal production has been limited for 15 years by the difficulty and the cost to generate transgenic farm animals. Gene addition can be achieved by DNA microinjection into one-cell embryos in rabbit and pig. In ruminants, gene addition can be achieved by classical transfection in fetal cells further used to generate cloned transgenic animals. The cloning techniques have been used successfully to replace gene by homologous recombination in sheep and can be extended to goat, cow, pig and expectedly in rabbit. This may lead to precise gene inactivation or allele replacement. In birds, several techniques can be used to generate transgenics. None of these techniques can presently be used routinely to improve breeding. Transgenesis in farm animals is expected to protect animals against diseases, to reduce rejection of pollutants, to optimize digestion, to improve growth and fertility, to optimize meat and milk composition, etc… The production of pharmaceutical proteins in transgenic animals and the use of pig organs for xenografting are not expected to have any significant direct impact on animal production.