Increased intake of mono- and disaccharides by Reeves's muntjac (Muntiacus reevesi). Effect on gastrointestinal tract structure and function and blood parameters.

The aim of this study was to determine the effect of an increased mono- and disaccharide (MD) intake on selected functions and structure of the gastrointestinal tract (GIT), and selected blood parameters in Reeves's muntjac (Muntiacus reevesi), a small browsing ruminant. Eighteen male muntjacs were fed diets consisting of lucerne (ad libitum), a high fibre pellet (100 g/day) and wheat bran (30 g/day) without (MD0) or with addition of 10 or 20 g of glucose, fructose and sucrose mixture/day (MD10 and MD20, respectively) for 14 days. MD dosages were set to increase intake of these saccharides by 25% and 50% relative to MD0, which resulted in a range of water-soluble carbohydrate content in the consumed dry matter from 7% to 12%. Compared to MD0 animals, MD20 animals had a lower dry matter intake, a higher MD concentrations in the reticulorumen (RR), abomasal and small intestinal digesta, higher ruminal butyrate concentration, higher SGLT1 expression in the epithelium of proximal jejunum, higher plasma glucose, lower RR tissue weight but greater caecal tissue weight (p ≤ 0.05), and had or tended to have shorter papillae and lower mucosa surface area in the Atrium ruminis (by 44%; p = 0.02 and p = 0.10, respectively); MD10 animals tended to have higher MD concentrations in the abomasal and small intestinal digesta (p ≤ 0.10), and a higher amylolytic activity (p = 0.02) as well as a tendency to lower xylanolytic activity in the RR digesta (p = 0.06). MD supplementation did not affect ruminal pH. In conclusion, low to moderate increase of MD intake increased MD concentrations in the RR, abomasal and intestinal digesta, and SGLT1 expression in intestinal epithelium, suggesting incomplete fermentation of those saccharides in the RR. MD supplementation dose-dependently affects structure of GIT in Reeves's muntjac.