Wooden blocks and straw as environmental enrichments for juvenile blue foxes (Alopex lagopus)

Abstract.

This study was designed to evaluate the enrichment value of a wooden block (30 cm long×4 cm in diameter) and straw for growing farm-bred male blue foxes (Alopex lagopus). Comparisons were made between animals provided with these enrichments at 7 weeks and 15 weeks of age. Various behavioural, physiological, and haematological variables as well as fur and teeth characteristics were assessed. The foxes showed significantly higher motivation to interact with the block than with the straw. The novelty response to block manipulation was higher when the block was given to foxes at 15 weeks than at 7 weeks of age. In straw groups no actual age effect was observed. Both the wooden block and the straw appeared to stimulate particularly the occurrence of play behaviour, which can be considered an indicator of good welfare. Significant differences were not found between the experimental groups in the novel object (ball) in-cage test. However, a slight tendency for increased explorative activity and shorter latency to object sniffing in the open field test were evident in the block animals. The wooden block was found effectively to prevent the accumulation of dental plaque and development of hypertrophia gingiva. However, both the block and the straw markedly increased the incidence of hyperaemia in the mucous membrane of the stomach and intestine. This may explain the lower weight development in these groups than in the controls. Significant differences were not found between the experimental groups in blood screen (haemoglobin, white blood cells, red blood cells, haematocrit) or in the cortisol:creatinine ratio analysed from 24-h urine. The body-weight-related adrenal weight, however, tended to be lowest in the block animals. Furthermore, the presence of a wooden block in a cage significantly reduced the amount of oral stereotypies during the latter part of the growing season. Significant differences did not exist in economically important fur characteristics (quality, mass, cover). It is suggested that further studies on alternative chewing objects should be conducted before introducing such environmental enrichments into farming practice.