An argument for genetic engineering

Soon we will have cows that are immune to mad cow disease. We’re not about to engineer cows on a large scale, and probably we don’t need to; my interest is in how this upsets the usual spectrum of ecological worries. I’ve found that people who fear mad cow disease also tend to fear genetic engineering of animals. But now, which way to turn? It reminds me of those reports saying we need not fear global warming, because we will run out of oil in the meantime!