Standard growth and diarrhea-associated growth faltering in captive infant rhesus macaques (Macaca mulatta)

Reference growth studies of captive rhesus macaque infants have not accounted for diarrhea and the potential for growth stunting or growth faltering. Healthy infants without diarrhea could be used to build a standard growth chart and a tool used to detect growth faltering associated with diarrhea. We hypothesized infants who develop diarrhea during the first year of life would experience decreased linear weight gain compared to healthy infants, and we used healthy infants to establish standard growth of male and female infants. We hypothesized the lower 3rd percentile of standard growth would be cut-off criteria used in screening for diarrhea-associated growth faltering. Using a retrospective cohort of 6,510 infant weight records in a multiple linear regression, daily weight gain through the first year of life was determined by sex, housing type, and health status. Male standard growth was 4.1 g/day (95%CI: 4.0-4.2 g/day) in corrals and 4.7 g/day (95%CI: 4.5-4.8 g/day) in shelter housing. Female standard growth was 4.0 g/day (95%CI: 3.8-4.2 g/day) in corrals and 4.4 g/day (95%CI: 4.0-4.7 g/day) in shelter housing. Diarrhea was significantly associated with decreased linear weight gain by up to 34% during the first year of life. Odds of growth faltering of infants, defined as those falling below the 3rd percentile of standard growth, were at least 8.9 higher given a history of diarrhea compared to healthy. The growth faltering cut-off criteria had a sensitivity of at least 53% for males and females to screen for diarrhea in infants between 6 and 12 months in shelters housing. Interinstitutional collaborations of infant rhesus macaque weight records would refine the standard growth charts and cut-off criteria, and additional morphometric data would provide a more nuanced picture of growth stunting.