The use of body condition scoring—Old-World nonhuman primates (2025)

Brooks, K., Teti, M.

Abstract

Body condition scoring (BCS) is defined as a subjective semiquantitative method of assessing body fat and muscle [JAALA, 51(1) 83-93]. Used as a management tool designed to assess the physical state of an animal, its musculature, body reserves and fat accumulation, is useful to assess overall health, production and dietary management and can be a predictive factor in disease risk and outcome. BCS and bodyweight are two common methods used to assess the health of Old-World nonhuman primates (NHPs). While both techniques provide valuable information, they differ in terms of their approach and the type of data they generate. Body condition takes into consideration the shape, size and body composition of an animal. This approach allows for a more holistic assessment of an animal’s overall health and wellbeing. In contrast, bodyweights are quantitative and objective measurements that do not account for variations in shape, size or body composition. While bodyweights provide a straightforward numerical value, they may not accurately reflect an animal’s true level of health. For example, body composition varies significantly between males and female, particularly concerning muscle mass. Rhesus macaques (Macaca mulatta) are moderately dimorphic in body mass. Males are ~44% larger than females (Kimock et al., 2019), which can lead to noticeable differences in bodyweight. This disparity is not merely a reflection of physical strength or fitness but is rooted in biological differences such as hormonal influences and genetic predispositions. Consequently when assessing bodyweight alone, females may appear considerably smaller than their male counterparts. Despite these apparent size differences, it is essential to recognise that smaller bodyweight does not inherently equate to poor health or fitness levels among females. BCS serves as a valuable tool in evaluating overall health regardless of size or gender. BCS provides an objective measure that assesses fat coverage and distribution on an animal’s body, allowing for a more nuanced understanding of health beyond mere weight metrics. In many cases, female bodies may exhibit lower muscle mass. However, with appropriate BCS evaluation it can be determined that they maintain good health status. BCS involves a visual and hands-on assessment, with a numerical grading system using the BCS charts (Figures 1 and 2) based on Macaca mulatta as a model. It is reliant on visual observations and physical palpation to assess the overall body condition of the macaque. The hands-on approach allows for a more accurate evaluation compared to only relying on visual cues alone; additionally, the use of numerical grading system provides a standardised way to quantify to an animal’s body condition, allowing for easy comparison between individuals.