DIGESTIVE PHYSIOLOGY OF WILD CAPYBARA

The capybara (Hydrochaeris hydrochaeris) is a hindgut fermenter whose digestive efficiency is comparable to that of ruminants on similar die ts. It is an interesting case for study because it is the largest caec um fermenter and uses coprophagy as part of its digestive strategy. It practices coprophagy in the early morning and forages and defaecates in the evening. Its anatomy is well known but the limited information available about its digestive physiology has been obtained from captiv e animals. In this work we studied the capybara's digestive physiology , using microbial and chemical information from samples taken from wil d capybaras in the early wet season in the morning (0600-0700 hours), noon (1200-1300 hours) and evening (1800-1900 hours), key points in th e digestive cycle. Bacteria (cellulolytic and non-cellulolytic) and pr otozoa were present in high concentrations in the caecum and colon. Th ere were no significant differences in nitrogen concentrations between digestive tract compartments in the coprophagy period (0600 hours), b ut in the other two periods nitrogen concentrations were significantly higher in the caecum than in the stomach and colon. This is suggestiv e of selective retention of microbial cells with fluid digesta in the caecum and of cecotrophy (the production of two distinctly different k inds of faeces - one kind called cecotrophes formed from caecal conten ts and ingested), The capybara hindgut (caecum and colon) with its con tent, was heavier during the dry season (period of poor diet quality) than in the wet season, but there were no significant seasonal differe nces between the stomach or small intestine and their contents. This s uggests changes in the capacity of the hindgut, the site of microbial fermentation, related to seasonal variation in resource quality.