Sir, - There has been a lot of publicity about the wonders of genetic engineering and cloning, with Polly, Dolly, etc heralded as scientific successes. However, little has been said about the serious animal welfare problems associated with these techniques. We do not see pictures of the many failures, or of the invasive surgical procedures used to produce genetically-engineered animals.

In reality, animal genetic engineering is a hit and miss affair. Of the 50,000 to 100,000 genes which make up a farm animal, the purpose of only about 2 per cent is known. Adding genes from other animals is like playing with a chemistry set that has all the labels removed. Except that in animal genetic engineering, the experimental material is living creatures which can suffer and feel pain when the experiments go horribly wrong.

For example, although the cloned lambs Megan and Morag looked normal, in fact, the majority of the cloned lambs in that series of experiments had malformed internal organs. In the experiments reported in February 1997 which produced the cloned sheep, Dolly, 148 out of 156 implanted embryos failed to survive. In the experiments which produced Polly, another cloned sheep, of the 14 foetuses alive at 60 days of pregnancy, only five developed into lambs which survived for more than two weeks after birth. Some lambs were stillborn, and one had a heart defect and was killed at two weeks old.

The problems are not confined to sheep. In 1994, reports emerged of a calf which was given genetic material usually found in a chicken. At eight weeks old, the calf seemed all right, but at 15 weeks the animal was no longer able to stand up and was destroyed. The calf's muscle development had completely broken down. Genetically-engineered salmon with added "anti-freeze" genes were coloured green and died of gill and cranial deformities. And pigs which had added cow or human genes in an effort to make them grow quicker suffered lameness, ulcers, damaged vision and heart and kidney ailments.

People might be quite shocked to see the unnatural methods used to produce a genetically-engineered animal or clones. This often involves invasive surgery and the sacrifice of temporary "foster mothers". The usual technique used to clone animals is as follows. Sheep that are to be egg donors are given hormone injections. The eggs are then removed by surgery. After these eggs are cloned, it is common for the cloned embryos to be placed into a temporary recipient sheep using surgery. Later, these temporary "foster mothers" are killed, and the embryos are removed and examined. They are then placed into a surrogate mother, again using surgery. Clearly, cloning an animal is far from a natural process.

Compassion in World Farming is campaigning for a moratorium on animal genetic engineering until there has been full public debate, and until the animal welfare problems have been addressed and the ethical implications of creating artificial animals has been fully explored. - Yours, etc., Mary-Anne Bartlett

Director, Compassion in World Farming, Ireland, Hanover Street, Cork.