High fiber/low sugar: effect on regurgitation & reingestion in silverback gorilla

Citation

Frost AM, Kelly L, and Papstein-Novak T. 2025. High fiber/low sugar: effect on regurgitation & reingestion in silverback gorilla. In Treiber K, Brooks M, D’amato-Anderson J, Nylander J, Eds. Proceedings of the Sixteenth Conference on Zoo and Wildlife Nutrition, AZA Nutrition Advisory Group, Oklahoma City, OK.

Abstract

Regurgitation and Reingestion (R/R) is a behavioral phenomenon that occurs in captive, non-human primates. This behavior can be negatively viewed by the public and, has been found within recent years to potentially contribute to periodontitis and ulceration of skin, due to the acidic content in regurgitant material having a much higher pH than when originally ingested.  With the aim of reducing occurrences of R/R in our 36-year-old silverback western lowland gorilla (Gorilla gorilla gorilla), Togo, we initiated a diet change consisting of reduced sugar (swapping high sugar pineapple and banana for moderate to low sugar berries) and added a fiber supplement (psyllium husk). In summer 2025, we monitored Togo during 12:00 to 13:00 due to this time period previously being noted as the timeframe he primarily exhibits R/R. Data was collected using Zoo Monitor and compared to data collected in fall 2024 when no dietary intervention was used. Data collection for this project has been completed and is currently being processed using data analysis software (RStudio). We hypothesize that the diet interventions will have decreased Togo’s R/R frequency.

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