Novelty exploration, baseline cortisol level and fur-chewing in farm mink with different intensities of stereotypic behaviour

Abstract

The present study aimed to examine the extent to which abnormal behaviours, stereotypic behaviour and fur-chewing, commonly used indicators of reduced welfare, are interrelated and linked to other welfare indicators in mink. Three groups were used based on behavioural observations, mink with no stereotypic behaviour (NST), mink performing stereotypic behaviour with only few repetitions (up to 4; ST1) and mink performing stereotypic behaviour with few (up to 4) and more repetetions (5 and above), in their repertoire ST2. Indicators of welfare included stereotypic behaviour observations, fur-chewing evaluation, baseline cortisol (faecal cortisol metabolites, FCM), and approach/avoidance behaviour in a novel object test and a stick test. There was no significant relation between the performance of stereotypic behaviour and fur-chewing. We found a higher level of FCM in the ST1 group with no tail-chewing behaviour and in tail-chewing mink in general, indicative of stress. However, unexpectedly tail-chewing mink were more explorative towards novel objects. The results supports that stereotypic behaviour and fur-chewing in mink are elicited by different environmental factors, suggested to be related to foraging and under-stimulation respectively.