Fritz, J., Maki, S., Nash, L. T. et al. 1992. The relationship between forage material and levels of coprophagy in captive chimpanzee (Pan troglodytes). Zoo Biology 11, 313-318.

Coprophagy scores were higher when chicken scratch or sweet feed [cracked corn, grain, rolled corn/barley] were available than when popcorn was available. Levels of coprophagy may be lowered by offering wadging materials [e.g., corn cobs, fruit pits, cardboard, fruit peels] with the forage.