(KG) SUSTAIN -- DENVER, CO (APRIL 19, 2007) -- Denver Zoo elephant keepers Dave Johnson, left, and Barb Jenkermeier, right, remove waste produced by two Denver Zoo female asian elephants named Dolly and Mimi. The zoo estimates that the elephants produce 5

(KG) SUSTAIN -- DENVER, CO (APRIL 19, 2007) -- Denver Zoo elephant keepers Dave Johnson, left, and Barb Jenkermeier, right, remove waste produced by two Denver Zoo female asian elephants named Dolly and Mimi. The zoo estimates that the elephants produce 5 full wheelbarrows of waste every day. The elephants are on a diet of fruit, grains and mostly hay. (DENVER POST PHOTO BY KARL GEHRING) (Photo By Karl Gehring/The Denver Post via Getty Images)