Sites of organic acid production and patterns of digesta movement in the gastro-intestinal tract of the raccoon

Abstract

Twelve raccoons were used to assess the movement of fluid and particulate digesta through their gastrointestinal tract and to determine the diurnal variations in organic acid levels for the various segments of the tract. Fluid and particulate markers were administered at the time of meal feeding. Animals were killed at given intervals after the administration of markers. The gastrointestinal tract was removed and divided into seven segments for measurement of markers, pH, volatile fatty acids (VFA) and lactic acid content. The results indicate a rapid transit of the digesta through the entire gastrointestinal tract, with a mean retention time of less than 24 hours for all fluid and particulate markers. Particulate markers up to 2 cm in length were passed rapidly, with limited retention within the tract, much unlike animals with greater gut complexity. The apparent requirements for gut complexity and digesta retention presumably necessary for digestion by gut microflora were not evident in the raccoon. However, even in the absence of these characteristics, microbial fermentation of the ingesta occurred, as evidenced by the levels of organic acids produced. Colonic VFA concentrations achieved levels comparable to levels observed in the ruminants' foregut and the large intestine of the pony. Lactic acid was found throughout the entire gastrointestinal tract.