Large intestinal capacity, retention times, and turnover rates of particulate ingesta associated with extensive large-colon resection in horses.

Fecal excretion of a particulate marker, ytterbium (Yb), was evaluated in 9 horses before surgery and 3 weeks, 3 months, and 6 months (4 trials) after sham-operation (group 1; n = 3) or extensive large colon resection (group 2; n = 6). Fecal excretion curves of total Yb excretion, loge Yb excretion, % Yb excretion, loge % Yb excretion, and cumulative % Yb excretion were evaluated, and kinetic analysis was performed on the loge Yb excretion curves to detect mixing pools and to calculate the fractional rate of particulate passage, turnover rate, and pool size. Calculations were performed to determined transit time, mean overall retention time, adjusted mean retention time, peak time, and disappearance time. Values were statistically analyzed to determine differences between groups and among trials (P less than 0.05). Group-2 horses had significantly shorter transit, peak, and mean overall retention times, compared with preoperative values and with values for group-1 horses. Two mixing pools were identified: a slower emptying pool of 5.7% hour-1 (k1) and a faster emptying pool of 12.3% hour-1 (k2). The rate of passage from the first pool (k1) was not altered by colon resection, and was interpreted as being most influenced by the cecum. In further support of this interpretation, the capacity of the k1 pool approximated the capacity of the cecum (17 L). The capacity of the k1 pool significantly expanded by 6 months in the resected horses. the rate of passage from the second pool (k2) significantly increased initially after colon resection (3 weeks and 3 months), but returned to preoperative values by 6 months.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of the effects of psyllium and wheat bran on gastrointestinal transit time and stool characteristics.

Gastrointestinal transit time, frequency of defecation, stool weight, and stool consistency were studied in 12 subjects who were each given fiber supplements containing wheat bran, psyllium gum, a combination of wheat bran and psyllium gum, or a low-fiber control for 2 weeks. Gastrointestinal transit time was measured using four different markers: plastic pellets, chromium mordanted bran, cobalt-ethylenediamine-tetraacetic acid, and terbium oxide. The wet weight and dry weight of stools were measured, and a questionnaire accessed subjects' perceptions of the consistency of their stools. Fiber supplementation decreased transit time and increased the daily number of defecations and the wet weight and dry weight of stools. Bran had a greater effect on transit time than psyllium. Psyllium had a greater effect on the amount of water found in the stools and the total stool weight. On the days that stools were passed, 50% of the daily stool ratings were scored as "hard" when subjects received the control supplement. Less than 10% of the ratings were scored as "hard" when subjects received the high-fiber supplements. The type of marker used did not significantly affect the transit time measured.

Mean transit time measurement by analysis of a single stool after ingestion of multicolored plastic pellets.

Mean transit time (MTT) was measured in 12 females and served as a standard to evaluate the validity of different methods of estimating transit by analysis of a single stool (SST). Each subject consumed three different fiber supplements and a low-fiber control for 14-d periods. On days 4-8 of each period, subjects were given 20 plastic pallets, which varied in color each day. SST was calculated using from two to five sets of colored pellets and different criteria for designation of the stool to be analyzed were compared. Results indicate that the following modifications in the SST method originally proposed by Cummings and Wiggins will result in improved prediction of MTT: 1) Increase the days of dosing from 3 to 6.2) Collect for study the first stool passed 3 h after the last dosing. 3) Include all pellets identified in the selected stool in the SST calculation.

Effect of psyllium gum and wheat bran on spontaneous energy intake.

Energy intake, fecal energy output, and gastrointestinal symptoms were measured in 12 females who consumed either approximately 23 g/d supplementary fiber or a 4 g/d fiber control. Fiber supplements were crackers containing psyllium gum, wheat bran, or a combination of the two fiber sources. After 1 wk on the control cracker, subjects consumed the three high-fiber crackers and the control cracker for 2-wk periods in a balanced design. Gum and combination supplements gave increased bloating and flatulence. Increase in abdominal pain was reported with gum supplement. Mean daily fecal energy was 96 kcal/d with control crackers and was increased by 63 kcal with high-fiber crackers. Gum and combination supplements significantly decreased intake of digestible energy by 153 and 115 kcal/d, respectively. This suppression was not dependent upon fiber intolerance. Wheat bran supplement had no effect on energy intake.