Wiard, J. 1992. Reduction of regurgitation and reingestion (R&R) in lowland gorillas at the Oklahoma City Zoo. Gorilla Gazette 6(3), 6-7.

The addition of browse or hay to the diet of captive gorilla reduces the occurrence of R&R [regurgitation-reingestion]. Novelty items tend to reduce R&R for short periods of time. Manipulation of how and when food items are presented reduces R&R.