Finding Balance: The rise of zoo animal nutrition [Das Gleichgewicht finden: Der Aufstieg der Tierernährung in Zoos]

Zoo animal nutrition, as an applied scientific field, is roughly a century old and has seen significant development and impact in changing feeding practices within modern zoos. Whilst the history of zoo animal nutrition has been documented within the profession, how and why zoo feeding and zoo nutrition has changed has generally not be addressed. This paper adds to this existing literature by providing an historicised sociological interpretation of the development of zoo animal nutrition. Zoo animal nutrition as an applied science has developed at quite a pace since its establishments in the early 20th century. Modern zoo feeding practices have changed with the knowledge created by zoo animal nutrition but also in line with the zoos’ evolution from statements of imperial power to spaces of scientific curiosity and entertainment to conservation-oriented institutions focused on planetary health. The origins of scientifically informed zoo nutrition can be traced back to the work of the Penrose Research Laboratory (est. 1901) at Philadelphia Zoo. Investigations into causes of death of the zoos collection led by Dr Herbert Fox enabled research by Dr Ellen Corson-White who linked dietary deficiencies to disease and mortality. These findings were further developed by Dr Herbert Ratcliffe who developed “zoo cake” – the first manufactured complete feed for zoo animals – which aimed to standardise and optimise nutrition while reducing disease. The adoption of manufactured diets sparked a philosophical and practical debate, exemplified by the 1966 International Zoo Yearbook exchange between Ratcliffe and Heini Hediger. Ratcliffe prioritised internal health metrics and efficiency, whereas Hediger warned against behavioural impoverishment and “domestication” through artificial feeding. This clash crystallised the epistemic divide between pathological science and ethological observation, a tension that persisted through the century. During the final few decades of the 20th century, zoo animal nutrition entered a period which can be characterised as a “nutritional turn.” This period would see attempts to institutionalise the field through conferences such as the Dr Scholl Nutrition Conferences and the 1999 European Zoo Nutrition Research Group meeting. Zoo feeding increasingly integrated behavioural ecology with nutritional science. The period also saw the emergence of the zoo nutritionist as an employed position in zoos, although uptake across institutions remained limited. Present-day zoo nutrition reflects a negotiated balance between evidence-based nutrient provision and the promotion of natural feeding behaviours developed during the nutritional turn with more traditional approaches. The contemporary zoo nutritionists are “ark diplomats”, highlighting their mediating role between science, husbandry practice, institutional priorities, and animal welfare. While the field has advanced markedly since its early 20th-century roots, institutional integration remains incomplete. Greater recognition and empowerment of zoo nutrition expertise is essential to meet the intertwined challenges of animal welfare, biodiversity conservation, and planetary health in the 21st century.