Main content

The welfare significance of inactivity in captive animals, using mink as a model

Show full item record

Title: The welfare significance of inactivity in captive animals, using mink as a model
Author: Meagher, Rebecca K.
Department: Department of Animal and Poultry Science
Program: Animal and Poultry Science
Advisor: Mason, Georgia
Abstract: Captive animals are sometimes very inactive, which can elicit concern for their welfare. However, inactivity is difficult to interpret in terms of welfare, since while some forms reflect chronic fear (hiding), apathy, or depression-like states, others reflect positive states (e.g. relaxation). This thesis aimed to determine whether high levels or particular sub-types of inactivity indicate poor welfare in fur-farmed mink (Neovison vison), and to identify the specific psychological states involved. These questions were addressed by studying individual differences within populations on three commercial farms, and comparing mink in standard, non-enriched cages to those in enriched cages. Two hypotheses were tested on farms: that the most inactive mink experience chronic stress, and that this would impair reproduction. Inactive females did have smaller litters, a difference that was not attributable simply to their greater body fat. However, there was no evidence of endocrine stress nor increased fear in “glove tests”, and their kits also grew more quickly. This suggests that inactive females do not experience more chronic stress than active females do. Tests of responsiveness to stimuli (measured in terms of contact and orientation) showed that, compared to mink in enriched cages, non-enriched mink were more responsive to all types of stimuli, especially neutral ones. This finding is inconsistent with the hypothesis that inactive individuals in these conditions are apathetic or depressed; instead, it supports the alternative hypothesis that non-enriched cages induce boredom. However, this boredom-like hyper-responsiveness did not co-vary with inactivity levels. Finally, non-enriched cages did not consistently elevate total inactivity. However, they did induce specific types: inactivity in the nest box, lying alert (vs. sleeping), and lying belly down rather than curled up were all more common than in enriched cages. Inactivity in the nest box may reflect hiding; it seemed linked to fearfulness in glove tests and to endocrine stress responses. In sum, while non-enriched conditions induce poor welfare, they do not increase overall inactivity; furthermore, within populations, the welfare of highly inactive individuals is no more compromised than that of their more active counterparts. However, subtypes of inactivity provide more information about welfare than total inactivity.
Date: 2011-12-22

Files in this item

Files Size Format View
meagher 2011 phd thesis.pdf 9.882Mb PDF View/Open

This item appears in the following Collection(s)

Show full item record