Do Enrichment Practices Help Nonhuman Primates (NHPs) in Laboratory Settings?

This blog post was written by Simran Prasad

In 2019, over 4000 nonhuman primates (NHPs) were used for research, teaching and testing purposes and this number is expected to grow in future years. Even though the physical wellbeing of NHPs is taken into consideration during animal husbandry procedures, their activities and behaviours do not always reflect a healthy condition. Rigid research protocols and laboratory environments may create a stressful atmosphere for NHPs which disturbs the expression of their natural behaviours and compromises their well-being. In view of improving the welfare of captive animals, research centers use and test the effectiveness of various types of enrichment. The objective of implementing enrichment practices is to go beyond the animals’ basic needs. Given that NHPs are intelligent animals, enrichment plans need to be strategically designed in order to cater to their continuous need for meaningful and functionally stimulating opportunities to manifest normal behaviours.

Generally, NHPs that received enrichment displayed more favourable behavioural profiles. Environmental enrichment was implemented by providing objects or modifying the enclosure of the monkeys.

The results showed that once the novelty of an object such as a toy and a mirror was lost, it became uninteresting to the monkeys, whereas outdoor enclosures or the addition of perches would provide the opportunity to express natural behaviours.

Considering the fact that macaques and marmosets are social animals, housing them individually can generate several issues. Studies that tested social housing as enrichment and placed them in pairs or in groups enabled them to engage in social activities like grooming and playing with each other.

Some researchers tried using different foods, feeders and foraging devices to encourage food-related activities. They were successful in keeping the NHPs occupied by elongating their foraging time and hence reducing injurious behaviours.

The use of technology as an enrichment mostly involved computers in training the subjects to perform various tasks; this helped successfully alleviate stereotypic and harmful behaviours. Occupational enrichment aims to engage the cognitive skills of NHPs; most studies used puzzle feeders, computer tasks and audio-video stimuli to keep their minds busy. While technological and occupational enrichment were mostly used and effective in stimulating the primates’ cognition, the most potent types of enrichment were environmental, social and food enrichment as they provided opportunities to manifest natural behaviours.

The benefits of enrichment practices are reflected in the subject's behavioural improvement, which favours their addition to laboratory management routines. The importance of enrichment practices is reflected in the effectiveness of correcting harmful behaviours that are seen in NHPs placed in laboratory settings. When properly designed, enrichment plans do not interfere with animal husbandry tasks and additionally allows a more favourable environment to carry out research-related tasks and improves the primates’ well-being.