ENDOCRINOLOGY IN PRIMATE WELFARE AND ENRICHMENT

Abstract

This article employed a mixed experimental design based on different studies with endocrinological measures of endocrinological stress reactions and welfare measures in captive macaque monkey (Macaca mulatta) or capuchin monkey (Sapajus apella) in various types of enrichment.  Three enrichment conditions, i.e., physical, cognitive and combination, were provided in random weekly blocks over twelve weeks. Welfare has been quantified based on determining faecal cortisol levels as well as observing animal behaviour.  To carry out the quantitative study we normalised the cortisol data using z-score normalisation and used mixed-effects regression modelling in analyzing the physiological stress influenced by different types of enrichment and behavioural markers.  We employed qualitative behavioural coding in order to identify activity patterns that were linked with the welfare.  These findings demonstrated that the combination of physical and cognitive enrichment resulted in the largest decrease of cortisol z-scores, and large increases in exploratory and affiliative behaviours and large decreases in stereotypical patterns.  Statistical modelling revealed that the negative correlation between positive behavioural engagement and cortisol is great (p < 0.05). It implies that composite enrichment strategies reduce physiological stress to a very high level.  These findings indicate that a combination of endocrinological and behavioural measures as a welfare assessment tool is useful, but they also provide us valuable information on how to better look after captive primates.  The analysis demonstrates that zoological and conservation environments require multifaceted frameworks of welfare assessment that are conducive to evidence-based forms of enrichment that contribute to good physical and behavioural vitality.