Different studies are funded in different ways. I would imagine for the most part that animal studies are privately funded versus scientific studies on health and the environment. Government wise knowing how many times a rabbit can breed in a day can come from interest in crop production and the damage they can do. If things like rabbits or locust are a threat to the food chain then it'd matter and you'd want to know exactly what you are up against. All threats are not man made. Monkeys are often used in lab experiments as they have the closest relevance to man....knowing men maybe they want to observe what repeated friction upon the penis can do....lol...I am just kidding, just thought I'd throw in a bit of humor.