title: Urinary C-peptide measurement as a marker of nutritional status in macaques.
abstract: Studies of the nutritional status of wild animals are important in a wide range of research areas such as ecology, behavioural ecology and reproductive biology. However, they have so far been strongly limited by the indirect nature of the available non-invasive tools for the measurement of individual energetic status. The measurement of urinary C-peptide (UCP), which in humans and great apes shows a close link to individual nutritional status, may be a more direct, non-invasive tool for such studies in other primates as well and possibly even in non-primate mammals. Here, we test the suitability of UCPs as markers of nutritional status in non-hominid primates, investigating relationships between UCPs and body-mass-index (BMI), skinfold fatness, and plasma C-peptide levels in captive and free-ranging macaques. We also conducted a food reduction experiment, with daily monitoring of body weight and UCP levels. UCP levels showed significant positive correlations with BMI and skinfold fatness in both captive and free-ranging animals and with plasma C-peptide levels in captive ones. In the feeding experiment, UCP levels were positively correlated with changes in body mass and were significantly lower during food reduction than during re-feeding and the pre-experimental control condition. We conclude that UCPs may be used as reliable biomarkers of body condition and nutritional status in studies of free-ranging catarrhines. Our results open exciting opportunities for energetic studies on free-ranging primates and possibly also other mammals.
authors.affiliation: Jr Research Group Primate Sexual Selection, Reproductive Biology Unit, German Primate Centre, Goettingen, Germany.
authors.forename: Cédric
authors.initials: C
authors.lastname: Girard-Buttoz
authors.forename: James P
authors.initials: JP
authors.lastname: Higham
authors.forename: Michael
authors.initials: M
authors.lastname: Heistermann
authors.forename: Stefan
authors.initials: S
authors.lastname: Wedegärtner
authors.forename: Dario
authors.initials: D
authors.lastname: Maestripieri
authors.forename: Antje
authors.initials: A
authors.lastname: Engelhardt
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000652:urine; D015992:Body Mass Index; D001835:Body Weight; D002096:C-Peptide / Q000097:blood / Q000652:urine*; D004032:Diet; D005247:Feeding Behavior; D005260:Female; D006799:Housing, Animal; D008251:Macaca / Q000652:urine*; D008297:Male; D009752:Nutritional Status / Q000502:physiology*; D012885:Skinfold Thickness; D013045:Species Specificity
chemical_list: D015415:Biomarkers; D002096:C-Peptide