Motor activity in the large intestine of the pig related to dietary fibre and retention time.

Abstract

1. Large intestine electromyograms were recorded from four pigs receiving successively three diets containing different amounts of fibre (standard cereal diet, milk substitute and milk plus 170 g bran/kg). For each diet the mean retention time of a marker added to one meal was determined. Three occurrences of spontaneous constipation were also studied.2. Slow waves were observed in the colon only during 10% of the recording time at a frequency of 10.3 ± 1.1/min. Two kinds of spiking activity were recorded on the colon: short spike bursts of 0.5–2 s duration and long spike bursts of approximately 7 s duration. Long spike bursts alone were recorded on the caecum.3. The mean retention time of the marker was 40 h on the standard diet, 120 h on the milk-substitute diet, and 66 h on the milk plus bran diet.4. On the standard diet, approximately 1500 colonic long spike bursts were recorded daily and short spike bursts occupied 15% of the recording time. On the milk diet, the number of long spike bursts decreased significantly (P < 0.01) to 500/d and the short spike bursts increased significantly (P < 0.05) to take up to 21% of the time. Intermediate values (1100/d and 19%) were observed when bran was added to the milk diet. The lowest values for long spike bursts (300/d) and highest values for short spike bursts (44% of the time) were observed in constipation.5. It is concluded that long spike bursts are associated with propulsion of intestinal contents and that short spike bursts are non-propulsive.