A lot of these farms use the manure to fertilize fields where they grow the food for the animals.
There used to be some hog farms that were two story. Feed hogs corn on the top floor and the hogs below ate the manure from the top floor. FDA changed regulations and made the practice illegal.
Reminds me of the Vietnamese genius in Saigon who got the garbage removal contract for NCO and O Clubs at Ton San Nhut Airbase. He hauled the garbage to his pig farm which was next to his fish ponds which got the pig manure. He made a fortune selling pork and fish to the clubs. closed cycle money machine!!
***Feed hogs corn on the top floor and the hogs below ate the manure from the top floor. ***
I remember operations like that. they fed corn to cows, then ran hogs behind the cows to eat the undigested corn in the manure, then ran chickens behind the hogs to eat that manure.
Then they mixed the chicken manure with ground corn and fed it to cows.