Lake pigments facilitate analysis of fecal cortisol and behavior in group-housed macaques

Fecal steroid analyses are becoming more popular among both field and labor atory scientists. The benefits associated with sampling procedures that do not require restraint, anesthesia, and blood collection include less risk t o both subject and investigator, as well as the potential to obtain endocri ne profiles that do not reflect the influence of stress. However, the utili ty of the fecal steroid method has been limited in field conditions because of problems associated with sample identification. Here, we present eviden ce that Lake pigments are a valuable tool for the identification of individ ual fecal samples from group-housed female cynomolgus macaques. Further, we present data that suggest that excreted cortisol can be assayed from such samples, leading to the finding that time of day of sample collection influ ences cortisol concentrations, with morning samples producing higher values (t = 2.769, P = 0.024). Finally, the collection of physiological data from group-housed animals permits the evaluation of the relationship between en docrine status and behavior. This study demonstrated that morning fecal cor tisol was significantly correlated with competitive and proximity behaviors , although not with rank in two stable social groups. In conclusion, the ut ility and validity of fecal steroid analyses continue to expand with furthe r investigations. (C) 2001 Wiley-Liss, Inc.