학술논문
The Comparative Effect of Occupational and Musical Enrichment on Fecal Glucocorticoid Metabolite Levels in a Captive Colony of Stumptail Macaques (Macaca arctoides)
Document Type
Academic Journal
Author
Source
Biology (Basel). February 2024, Vol. 13 Issue 2
Subject
Language
English
ISSN
2079-7737
Abstract
Author(s): Lilian Mayagoitia-Novales [1]; Ana Lilia Cerda-Molina (corresponding author) [1,*]; María Andrea Martín-Guerrero [2]; Emmanuel Muñoz-Zamudio [3]; Gema R. Estudillo-Mendoza [1]; Javier I. Borráz-León [1,4] 1. Introduction Primatological research in [...]
Environmental enrichment programs (EEP) are necessary to enhance animal welfare; specially, it has been shown that occupational EEP increases behavioral diversity and reduces aggression as well as abnormal behaviors, such as stereotypies. Most primates in the wild live in social groups characterized by dominance hierarchies. However, captive populations of primates, in zoos or laboratories experience problems such as lack of visual stimulus and restricted spaces to interact. So, captivity increases the probability of alterations in normal social behaviors and tends to produce distress, thus reducing the welfare of animals. The present study shows sex, age, and rank variations in the secretion of fecal glucocorticoid metabolites (fGCM) after introducing novel objects and playing relaxing musical sounds in the enclosures of stumptail macaques (Macaca arctoides). After introducing novel objects, adults showed high fGCM levels compared to juveniles and subadults, indicating a higher stress response to the novel stimulus; in contrast, music and occupational enrichment decreased fGCM levels only in middle-ranking macaques, suggesting a probable relaxing effect. Overall, our results highlight the need to consider age and social differences when planning primate enrichment programs. Environmental enrichment improves captive animal welfare by reducing stress-related behaviors. Previous studies in a captive colony of stumptail macaques (Macaca arctoides) reported a reduction of aggression, coprophilia, and stereotypic behaviors after an occupational enrichment program; however, the effect on stress hormones such as glucocorticoids has not been investigated yet. The goal of this study was to compare the effect of sex, age, and social rank on changes in fecal glucocorticoid metabolites (fGCM) after applying two kinds of enrichments (occupational vs. musical) in a captive colony of stumptail macaques. We collected 234 fecal samples from 25 stumptail macaques under the following conditions: (1) basal (no enrichment), (2) three weeks of occupational enrichment, and (3) three weeks of relaxing/classical music. The Generalized Estimated Equation Model showed an increase in fGCM levels after the occupational enrichment only in adult subjects (p = 0.003 compared to basal). The fGCM levels reached by the adults after the occupational enrichment was higher than that of juveniles (p = 0.002) and subadults (p = 0.02). Occupational and musical enrichment decreased fGCM levels only in middle-ranking individuals (p < 0.001 and p = 0.013, respectively). No sex differences were found. In conclusion, there were age and rank differences in individuals’ physiological reactivity to the effects of environmental enrichment which need to be considered when planning enrichment programs.
Environmental enrichment programs (EEP) are necessary to enhance animal welfare; specially, it has been shown that occupational EEP increases behavioral diversity and reduces aggression as well as abnormal behaviors, such as stereotypies. Most primates in the wild live in social groups characterized by dominance hierarchies. However, captive populations of primates, in zoos or laboratories experience problems such as lack of visual stimulus and restricted spaces to interact. So, captivity increases the probability of alterations in normal social behaviors and tends to produce distress, thus reducing the welfare of animals. The present study shows sex, age, and rank variations in the secretion of fecal glucocorticoid metabolites (fGCM) after introducing novel objects and playing relaxing musical sounds in the enclosures of stumptail macaques (Macaca arctoides). After introducing novel objects, adults showed high fGCM levels compared to juveniles and subadults, indicating a higher stress response to the novel stimulus; in contrast, music and occupational enrichment decreased fGCM levels only in middle-ranking macaques, suggesting a probable relaxing effect. Overall, our results highlight the need to consider age and social differences when planning primate enrichment programs. Environmental enrichment improves captive animal welfare by reducing stress-related behaviors. Previous studies in a captive colony of stumptail macaques (Macaca arctoides) reported a reduction of aggression, coprophilia, and stereotypic behaviors after an occupational enrichment program; however, the effect on stress hormones such as glucocorticoids has not been investigated yet. The goal of this study was to compare the effect of sex, age, and social rank on changes in fecal glucocorticoid metabolites (fGCM) after applying two kinds of enrichments (occupational vs. musical) in a captive colony of stumptail macaques. We collected 234 fecal samples from 25 stumptail macaques under the following conditions: (1) basal (no enrichment), (2) three weeks of occupational enrichment, and (3) three weeks of relaxing/classical music. The Generalized Estimated Equation Model showed an increase in fGCM levels after the occupational enrichment only in adult subjects (p = 0.003 compared to basal). The fGCM levels reached by the adults after the occupational enrichment was higher than that of juveniles (p = 0.002) and subadults (p = 0.02). Occupational and musical enrichment decreased fGCM levels only in middle-ranking individuals (p < 0.001 and p = 0.013, respectively). No sex differences were found. In conclusion, there were age and rank differences in individuals’ physiological reactivity to the effects of environmental enrichment which need to be considered when planning enrichment programs.