Let's say you want to protect the environment, and you are going to eat some meat, should you eat cows or pigs? Pigs. Let's say you care about animal cruelty. Pigs are smarter and more social than cows. A pig (or chicken) also seems to yield less meat per unit of animal suffering. That would imply it is better for animal welfare to eat cows rather than pigs. The conflict between environmental goals and animal welfare goals is one of the most significant underreported stories in this area.
I wonder how many people know that the best way to reduce your carbon footprint it to give up animal stuff, anecdotally I'd guess not many. Fortunately, I'm covered either way on this score. Unfortunately, I'm still rather attached to my dairy products.
Here are the two relevant links.