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Effects of environmental enrichment on stereotypic behaviour and reproductive success in American mink Neovison vison

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Title: Effects of environmental enrichment on stereotypic behaviour and reproductive success in American mink Neovison vison
Author: Díez León, María
Department: Department of Animal and Poultry Science
Program: Animal and Poultry Science
Advisor: Mason, Georgia
Abstract: The captive breeding of carnivores can be problematic for reasons that can be attributed to the chronic stress suffered in captivity. In addition, captive carnivores typically display high levels of stereotypic behaviour. These issues raise animal welfare concerns and also challenge the cost-effectiveness of ex-situ conservation breeding programs. This thesis is an investigation of the mechanisms by which environmental enrichment might improve reproductive success and reduce the performance of stereotypic behaviours in carnivores using a model species, the American mink (Neovison vison). This question was addressed in a research fur farm by studying the long-term effects of being raised in enriched versus non-enriched environments. Two hypotheses were tested: i) environmental enrichment increases individual reproductive success by reducing stress and/or normalising brain function; and, ii) stereotypic animals have compromised reproduction due to brain alterations induced by the impoverished captive environment that result in overall impaired behavioural control. Enriched animals showed physiological, anatomical and behavioural signs of improved welfare. In addition, enrichment improved male copulatory success by decreasing males' levels of stereotypic behaviour and repetitive tendencies. However, enrichment had no effect on female pre- or post-copulatory behaviour (with nest building perhaps being an exception). Other findings emerged from this study. Stereotypic animals were no worse or better off than non-stereotypic animals in either the enriched or non-enriched environments. This finding supports the hypothesis that within a given population, the performance of stereotypic behaviour reflects differences in response styles rather than differences in welfare. Moreover, different types of stereotypic behaviours seemed to have different causal basis, suggesting that when using stereotypic behaviours as welfare indices, different forms should be assessed separately. In conclusion, enrichment improved the welfare of mink as well as the reproductive performance of males by inducing changes in behavioural control. This has important implications for the millions of captive animals displaying stereotypic behaviours.
URI: http://hdl.handle.net/10214/8358
Date: 2014-08-29


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