Voluntary consumption of substances of unknown palatability by vervet monkeys: a refinement

Background  Pure compounds and herbal medicines, had to be administered orally to vervet monkeys for testing. A reliable method was sought to avoid daily gavaging. Methods  Substances were incorporated into the maize meal based diet of this facility for voluntary consumption. Food intake was monitored. Results  In all but one case, consumption of the treated food was in excess of 90%. In all cases, the purpose of the study was achieved. Habituation was usually only required to the vehicle, and was accomplished by incremental increases to the desired concentration. Aversion was overcome by the addition of a small amount of honey. Plasma concentrations of a compound metabolite could be measured in one case after gavage and food consumption, and were similar for both methods. Conclusion  The method enables reliable voluntary consumption of diverse substances. Since stressful gavaging is avoided, it is a valuable contribution to the 3Rs.