Putting the fighting animal issue aside. Human milk is 1% protein, yet baby can grow rapidly. High protein diet can lead to high cancer risk, rapid aging and slow down of our cell recycling. 2016 nobel medicine prize was awarded to a Japanese scientist who discover the process of autophagy. Autophagy is the key research area that can extend human life by 40 years. Instead of focus on protein, we need to focus on getting all 5 natural colors of whole food that are grown not born. And keep our protein intake low. 
RE: Where do you get your protein?