Effects of feeding fat-coated butyrate on mucosal morphology and function in the small intestine of the pig
As shown earlier, pig rations with high starch and purine content initiate mucosal hypertrophy by stimulating mitotic activity and DNA formation in the small intestine, whereas in the colon butyrate inhibits apoptosis and thus increases crypt depth. It was the aim of this study to combine these effects by targeting fat-coated butyrate into the small intestine where it usually does not occur, and to investigate effects on mucosal development and function. Three groups of five pigs were fed 3.6 kg/day of either a low-energy ration [deficit group, 6.6 MJ metabolizable energy (ME)/kg] or a high-energy ration (13.7 MJ ME/kg) that was supplemented with brewing yeast as a source of purines. The third ration was of high energy and contained purines and was additionally supplemented with coated butyrate (13.5 MJ ME/kg; 29 g calcium butyrate/kg). Rations were fed for 5 days. After killing, tissue samples were obtained from the proximal, medial and distal parts of jejunum for histology. Chyme samples were obtained from the ileum of all animals and used for sucrase determination. Villus size was not changed by feeding, but butyrate had an effect on plica height and area mainly in the medial jejunum. Plica area in the butyrate group (4.2 mm2) was significantly higher (p ≤ 0.01) compared with that of the deficit group (2.3 mm2) and high-energy group (2.7 mm2; p ≤ 0.01). For the butyrate group, sucrase activity in the ileum was 119.1 U/ml and thus significantly higher (0.05) compared with the high-energy group (61.7 U/ml) and the deficit group (28.0 U/ml; p ≤ 0.001). Targeting butyrate into the small intestine thus improves digestive and absorptive capacities. The mechanism probably is a specific effect on enterocyte mitosis which in turn leads to an increased plica size by crypt fission.