SALMON that grow four times as fast as nature intended, pigs with oversized hams and cows with giant udders are all part of the nightmare scenario where animal welfare comes second to food production.
Early attempts at genetically modifying and cloning domestic livestock resulted in the sort of gross deformities and public outrage that has tainted the entire field of farm-animal research.
The most notorious example is the Beltsville pig, named after a town in Maryland where the US Department of Agriculture attempted to produce faster-growing, bigger and leaner animals by inserting the gene for human growth hormone into pig embryos.
The results, however, were catastrophic. The animals developed a number of deformities, suffered severe arthritis and were evidently in great distress. It went down in the annals of animal experimentation as a public relations disaster.
Another research project in the 1980s attempted to produce cattle clones using the technique of embryo splitting - rather than the later technique of nuclear transfer used to create Dolly the cloned sheep.
An American biotechnology company attempted to commercialise the process but it had to be abandoned because the pregnant cows developed oversized foetuses.
Donald Bruce, an ethicist from the Church of Scotland's Society, Religion and Technology Project, said: "The increase of growth in animals has been a welfare issue for many years where selective breeding may lead to physiological abnormalities."
Attempts at producing genetically modified salmon, which can grow four times faster than normal, were carried out in a series of well-publicised experiments between 1996 and 1997.
Growth genes added to the fish enabled them to reach a weight of about 1 kilo (2.2 pounds) - and a length of (23 centimetres (9 inches) - within their first year, but environmental concerns rather than worries about animal welfare led to the project being abandoned.
"To be commercially viable they would have had to be grown in cages out at sea and there would be no guarantee that they could not escape," said Alastair Barge, managing director of Otter Ferry Seafish on Loch Fyne where the research took place.
Because of the increasingly hostile attitude towards GM food, especially when mixed with concerns over animal welfare, it is unlikely that companies in Britain will be able to convince the public of the need to boost meat and animal production using genetic technology.
However, there are serious attempts at trying to improve resistance to animal disease by altering certain genes that can boost the immune defences against infectious diseases.
John Webb, a geneticist at the Cotswold Pig Breeding company, said this sort of genetic enhancement could benefit both animals and farmers.
Pigs have already been selectively bred with a proven capacity to resist disease.
"We may get lucky and find some major genes here," Dr Webb said.
"It's very speculative and we'd have to be 100 per cent sure it would be in the animals qualified best interests before going ahead."
However, in the current climate of public mistrust, trying to prove that genetic modification is in an animal's interest may be difficult.
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