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Providing evidence to improve practice

Individual study: Removing milk from captive gorilla diets: The impact on regurgitation and reingestion (R/R) and other behaviors

Published source details

Lukas K.E., Hamor G., Bloomsmith M.A., Horton C.L. & Maple T.L. (1999) Removing milk from captive gorilla diets: The impact on regurgitation and reingestion (R/R) and other behaviors. Zoo Biology, 18, 515-528


This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.

Primates: Formulate diet to reflect nutritional composition of wild foods (including removal of domestic fruits) Management of Captive Animals

A before-and-after trial in 1999 in the USA (Lukas et al. 1999) found that replacing milk with fruit juice in gorilla Gorilla gorilla gorilla diets led to a significant decrease in voluntary regurgitation and reingestion of food or fluid from stomach to mouth and an increase in feeding behaviour. Regurgitation and reingestion were reduced from 11% of the time when milk was given to 8% of the time when fruit juice was offered instead of milk. In addition, the consumption of hay doubled from 10% to 22% of the time in the evening meal. The study used a withdrawal design method, in which 10 days of feeding non-fat powdered cow’s milk was followed by a treatment period of 10 days when milk was replaced with apple, orange or pineapple juice followed by a return to feeding milk for 10 days. Seven males and 12 females were studied for five minute sessions during a one hour period during the evening meal.    (CJ)