Mutant chickens that don't have feathers already exist. Provided they are kept warm, there doesn't seem to be much harm to them. From the farmers'
point of view they don't need as much food, so they can produce eggs and meat more cheaply.
Happy farm animals
Suppose we could genetically engineer chickens or any other farm animal to be "happy with their lot". If all we are concerned about is pain and suffering, such animals would be a good idea. However, if we are concerned with respecting animals, we might think this disrespectful to them or that it further reduces their status to that of a commodity.
Even more troubling, to many people, are blind chickens. These already exist and they didn't require genetic engineering to produce them - they are a natural mutation. Blind chickens seem to be better at coping with battery farming. They are less likely to harm one another by pecking. This means that, from an animal welfare point of view, it might be better to have blind chickens. Of course, when considering the value of a life, such chickens are clearly losing out.
Genetically modified mosquitoes sound like something out of a horror film. But there is a long history of using x-rays to sterilise male insects that cause human diseases. The sterile males are then released into the wild. The idea is that they breed with the females and fewer insects are born. The practice could probably be made much more efficient by genetically modifying the insects so they can't transmit the disease in question.
Protein farm animals
Many GM farm animals are being developed to make human proteins in their milk that can be used to treat sick people. People with cystic fibrosis may soon be benefiting from this sort of biotechnology. As the amount of protein each unwell person needs is small, you don't need many sheep, cattle or goats for this. The animals also tend to be very valuable, which means they get better veterinary attention than many farm animals.
New ways of using animals are being developed which involve neither genetic engineering nor cloning. Scientists are developing so-called "roborats", which have electrodes implanted in their brains. The rats can then be commanded to move from a remote control used hundreds of metres away. One possibility is that these rats might be used in mine clearance. The country's defence department research agency Darpa says: "The human is becoming the weakest link in defence systems".