Abstract
Severe diarrhoea, wasting and death were reported in a ten year old entire bull European bison in a wildlife park in England. Over two to three weeks its faeces had been become progressively more fluid and gradual weight loss had been noted. No pathogens were identified on faecal parasitology or bacterial culture, so more fibre was added to the diet, as this was thought to be beneficial. The bull would only eat browse (leaves from woody plants). This is unusual, as a report on range herbivores from Lyons et al. (2012) indicates the closely related American bison (Bison bison) usually eat mainly grass (81%), forbs (wildflowers, weeds, etc.) (12%) and browse only (7%). The bull then became acutely anorexic and died. An in situ necropsy was carried out by the private vet but there were no gross or subsequent histological findings of significance.

Key words: Copper, European bison, Bison bonasus, UK