What is a mega-dairy?

I recently reviewed my AP stylebook and was struck by the literal definition of the prefix "mega." Quoting from the stylebook:

"A prefix denoting 1 million units of a measure."

To my knowledge, no dairy in the U.S. has 1 million cows. If one did, they would own and milk 10 percent of the cows cared for in the nation. No wonder activists choose this prefix when affixing a label to dairy and other animal production. Caring for this many cows on one facility would be difficult. That's why none of these dairies exist. Dairy producers today have dairy sizes that permit efficient and safe care for their cows – regardless of size. That also can mean that not all family farms are small and that not all large dairies are factories.