I don't have any problems with the idea of raising animals for meat or other products such as milk, eggs or fur. I don't think it makes any difference whether the beasties are genetically engineered or not.
Of more concern is how the animals are treated. I don't like the idea of subjecting them to cramped conditions or pain just to make it a little bit more economical. I happily pay the extra few cents for "free range" eggs, for example, rather than buy the battery ones.
The danger here is that long term genetic engineering could conceivably result in grotesque beings that are constant pain, unable to move at all, just sit there their whole lives being milked for silk or whatever.
My only other concern with GM plants and animals is the same as introducing any species into an area where it is not indigenous. There is the possibility of them leaking out in the surrounding ecosystem and effectively taking it over.
...until the word "Maudling" is almost completely obscured.