Supportive nutrition for elderly chimpanzees: a case study on non-invasive supplementation in a group setting

Abstract

Ageing chimpanzees Pan troglodytes in zoological settings often experience physiological decline, including loss of body condition and muscle mass, which can negatively impact welfare and longevity. Over a three-year period, three elderly chimpanzees at Antwerp Zoo exhibited rapid and unexplained deterioration in body condition, whereas other group members remained in good health. Despite comprehensive diagnostic evaluations, including blood analyses and cardiac assessments, no underlying medical cause was identified. Given the importance of maintaining social bonds in older chimpanzees, individual intervention was implemented without disrupting group structure or routines. A high-protein, energy-dense, lactose-free shake was formulated to provide supportive nutrition, incorporating whey protein, rice milk, both soluble and insoluble fiber, and omega-3-rich fats, delivering approximately 1837 kJ ME per portion. The shake was administered individually as part of an established routine involving indoor herbal tea distribution, minimizing disruption and competitive behaviours. All three individuals showed marked improvement in body condition scores (from 2.0–2.5/10 to 3.8–4.2/10) over several months, alongside improved coat quality and increased alertness or activity. The intervention proved feasible, non-invasive, and socially compatible, offering a promising approach to geriatric care in great apes. However, long-term effects of sustained protein-rich supplementation remain unknown. Further research is needed to evaluate its impact on overall dietary intake and to determine its applicability across other great ape species.