Sixty-seven animals from eight primate species were used to assess improved husbandry techniques. The presence of woodchips as a direct-contact litter decreased inactivity and fighting, and increased time spent on the ground. Placing food in the deep litter led to further behavioral improvement. The use of frozen foods improved food distribution and reduced fighting in most situations, especially when it was buried in the litter. With time, the litter became increasingly inhibitory to bacteria. The results suggest that inexpensive ways of increasing environmental complexity are effective in improving housing for primates.
Chamove, A.S., Anderson, J.R., Morgan-Jones, S.C., & Jones, S.P. (1982). Deep woodchip litter: Hygiene, feeding, and behavioral enhancement in eight primate species. International Journal for the Study of Animal Problems, 3(4), 308-318.