An Opportunistic Study to Assess African Green Monkey (Chlorocebus sabaeus aethiops) Welfare Using Novel and Classical Biomarkers

The care and well-being of nonhuman primates (NHPs) in biomedical science have benefited from species-specific enrichment research. However, there remain few publications on African green monkey (AGM) welfare and husbandry. This opportunistic study aimed to explore the use of novel stress parameters alongside cortisol. Cortisol is a traditional stress biomarker, but its sensitivity to various factors calls for the study of supplemental stress biomarkers. Cortisol concentrations were analyzed in blood and fecal samples while potential novel biomarkers, lysozyme and β-endorphin, were analyzed in saliva and blood samples, respectively. The opportunistic design of this study introduced uncontrollable variables, although generalized linear mixed models with random and fixed effects were used to account for these factors. There were no significant changes in cortisol or β-endorphin levels, but a significant decrease in lysozyme levels was observed over time. The observed decrease in lysozyme levels indicates its potential as a biomarker for stress in AGMs. Future research should further explore lysozyme’s applicability as a biomarker for assessing animal welfare.