Steve Bircher, curator of mammals at the Saint Louis Zoo, told KSDK,

"It’s probably thousands of pounds that we collect and it’s recycled so we can use it as fertilizer and compost.”

Corrine Kozlowski, an endocrine lab technician, said,

"So we can determine whether an animal is pregnant or not from it’s poop. If it’s having regular reproductive cycles, so it allows us to time breeding appropriately for that animal. We can also look at whether an animal might be stressed based on hormones in the poop.”

Everything comes down to poo.