Effects of Feeding and Fasting on Fermentation Products in Digestive Organs and Metabolites in Blood in Microtus Montebelli

Effects of feeding and fasting on the fermentation products in the digestive organs, especially in the esophageal sac and caecum, and the metabolites in blood were studied in voles, Microtus montebelli. The results obtained are summarized as follows. (1) Mature voles-Microtus montebelli bred in our laboratory were divided into four groups, where each group was fed on one of the following rations: (A) hay-cubes alone, (B) hay-cubes and pellets for herbivores, (C) pellets for herbivores alone and (D) potatoes alone. Total VFAs of the esophageal sac contents were: (A) 4.30, (B) 4.65, (C) 4.06, (D) 3.31mM/dl. Acetic acid was the major fermentation product in the esophageal sac and attained about 90 percent of total VFAs, in groups (A), (B) and (C). Also, total VFAs in the contents of the fundic and pyloric regions of the stomach decreased remarkably to 1.77-1.37mM/dl. In group(D), fed on potatoes, a high concentration of lactic acid in the esoghageal sac contents was observed(3.78mM/dl), while those with high fiber ratios, (A), (B) and(C), were 1.28-2.67mM/dl. Total VFAs of the caecum contents were 9.72-10.42mM/dl and were hardly affected by the rations given. In this region, no lactic acid was detected. The molar percentage of acetic, propionic and butyric acid in the caecum was 10:1:2. (2) Blood glucose concentrations were(A) 63.8, (B) 81.0, (C) 91.3, (D) 77.4mg/dl. Hepatic glycogen contents in the voles were 10-20mg/dl. The plasma free fatty acid level was 0.600-0.732mEq/l. (3) The concentration of keton-bodies in blood and urine rapidly increased after fasting. 70% of the animals after 24hr-fasting, and 91% of the animals after 48hr-fasting showed ketosis followed by acidosis. After fasting, blood glucose concentrations decreased to 47.2mg/dl and hepatic glycogen was almost all consumed. The plasma free fatty acid level increased to 1.377mEq/l after 24hr-fasting and to 1.967mEq/l after 48hr-fasting.