cheezy - as for resistant strains of viruses, that holds true for all animals including humans if not even WORSE when it comes to human viruses! people are such freaks when it comes to being clean & going to the doctor for anything & getting pumped full of anti-biotics for anything or nonstop washing with germ killing soaps. our viruses are getting more resistant to our stuff. plus kids being so clean they'll have more problems down the road vs being exposed to germs at younger ages, one thing that helps is have a dog or cat.
as for cows, yea they might not be a smart choice for a meat source when it comes to the environment but what else can you do & try to wean the population off cows onto another meat source, but they'll always be needed for a milk source, people can raise more pigs/lamb/chickens/turkey/etc... instead.
but then again going green is not always better either! cost of things increase because of going green, even some new studies that say growing more corn will make it more humid in another location because corn sweats more than other crops.