Here ya go!
http://www.bls.gov/k12/html/gym_004.htm
Most people learn how to take care of animals on the job. Some animal caretakers can take a home-study course. Some animal trainers, however, need a college degree. Employers like workers who have had some training with animals before they give them a job.

Keepers in large zoos usually must have a college degree in biology, animal science, or a similar subject. They also should have worked with animals before. Other zoo training is the best, perhaps as a volunteer in a zoo or as a paid keeper in a smaller zoo.