Digging and its welfare implications for farmed blue fox

Abstract

Our study sought to clarify farmed blue foxes' (Vulpes lagopus) digging motivation on two different digging substrates, sandbox and plates. The plates were either on the wall or on the floor; the sandbox was always on the floor. A standard cage without any digging substrate was used as a control. We also evaluated the effects of the digging substrates on the animals' welfare. Each group comprised 20 juveniles kept in male-female pairs in conventional wire-netting cages. Our results showed that the motivation to dig for a specific goal (sandbox present) is no greater than that to perform digging behaviour per se only (plates present). There was a statistically significant difference in the dirtiness of the fur coat between the groups (P<0.001). The pelts originating from foxes kept in cages with a sandbox were dirtier than those from foxes kept in standard cages or in cages with a digging plate on the wall. Analyses of behaviour from video recordings and walking tests did not reveal any marked differences between the groups. Furthermore, the weight gain in animals with digging plates was similar to that in animals kept in standard cages. The variation in body weight development was highest in foxes with a sandbox. These findings indicate that the sandbox tends to have an adverse effect on body size. No statistical difference was found in haemoglobin, haematocrit, red blood cell or white blood cell values between the groups, and all the values were within a normal range. There was a slight tendency for the adrenal glands to be heaviest in the sandbox group (P = 0.1). The adrenal glands tended to be lightest in the group with a digging plate on the wall. A digging plate on the cage wall was considered to be the most suitable digging substrate for farmed blue foxes. A sandbox on the cage floor seems to be least acceptable because it makes the fur coat dirty and may cause problems for hygiene and thermoregulation. Key words: Vulpes lagopus, animal welfare, digging, fur animal production, motivation