Demonstrating coprophagy with passage markers? The example of the plains viscacha (Lagostomus maximus).
Coprophagy, or the ingestion of a certain fraction of the faeces, is a well-known strategy of small herbivores. However, the question of whether a particular species actually uses this cryptic strategy or not is not easily answered experimentally. In this study we introduce the use of ingesta passage markers as a tool to verify coprophagy in species where individual observation might be difficult. In two captive adult plains viscachas (Lagostomus maximus), we demonstrate recurrent excretion peaks for both a fluid (cobald-EDTA) and a particle (chromium-mordanted fibre) marker, the most parsimonious explanation for which is faeces re-ingestion. In addition, a literature review of graphical presentations of passage marker excretion revealed such recurrent marker peaks in a large number of studies; however, these observations were rarely explicitly contributed to a coprophagic digestion strategy. The widespread use of semi-logarithmic plots or cumulative marker excretion curves in displaying passage studies makes recurrent marker excretion peaks less evident. We conclude that passage markers offer a comparatively easy way of assessing the incidence of coprophagy. Due to the reported absence of coprophagy in rabbits, a species well-known for using this strategy, on high-protein, low-fibre diets, it is recommended that investigations of the occurrence of coprophagy should be made with animals fed challenging, high-fibre diets.
Clauss
Marcus
M
Division of Zoo Animals, Exotic Pets and Wildlife, Vetsuisse Faculty, University of Zurich, Winterthurerstr. 260, 8057 Zurich, Switzerland. mclauss@vetclinics.unizh.ch
Besselmann
Dorothea
D
Schwarm
Angela
A
Ortmann
Sylvia
S
Hatt
Jean-Michel
JM
D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D003303:Coprophagia / Q000503:physiopathology*; D005243:Feces; D012377:Rodentia / Q000502:physiology*
D015415:Biomarkers