Effect of weaning time and associated management practices on postweaning chronic diarrhea in captive rhesus monkeys (Macaca mulatta)

Objective: Our purpose was to assess the extent to which early weaning and other weaning-management factors affect development of postweaning chronic diarrhea in captive rhesus monkeys at the California Regional Primate Research Center between 1992 and 1995. Methods: Data for weaning, management, and onset of diarrhea were obtained from daily records. The Cox proportional hazard model was used to assess whether the risk of chronic diarrhea was related to early weaning. Results: Monkeys that were lighter at weaning had a threefold increase in risk of postweaning chronic diarrhea (P = 0.07), compared with that in heavier monkeys. An episode of preweaning diarrhea increased the risk of postweaning chronic diarrhea twofold (P = 0.08). Relocation of monkeys to outdoor facilities in the fall was associated with a fivefold decrease in risk (P < 0.001), compared with that of other seasons, and weaning in 1993 was associated with a twofold decrease in risk, compared with that of other years (P = 0.04). Conclusions: Multiple factors need to be considered for prevention of postweaning chronic diarrhea, including weaning weight, preweaning diarrhea, season weaned, and weaning conditions that change from year to year.