Method for Measurement of Gastrointestinal Absorption in Normal Animals, Combining Portal-Carotid Differences and Telemetered Portal Flow by Doppler Shift

Abstract

Abstract The Doppler Ultrasonic Blood Flow System was used to measure the portal blood flow rate (mean 40.9 ml/min/kg) in seven calves ranging from 3 to 22 weeks of age, fed milk at 5% of body weight twice daily. Absorption estimates of total sugars and glucose were made by combining portal flow and portal-carotid blood concentration differences. Telemetry of blood flow information permitted measurements on unattended animals in a normal environment. Mean velocity of portal flow one hour postprandial was increased 9.7% by feeding. Net absorption of total sugars and glucose determined from plots of portal-carotid concentration differences over the 12-hour feeding interval, combined with the portal flow rate, accounted for 60% (calculated as glucose and galactose) of the lactose intake. Glucose alone accounted for 41% of the lactose intake. Difference between the total sugars and glucose absorbed indicates that some galactose or lactose per se is absorbed. Data also indicate that 20 to 40% of the fed lactose is not accounted for as absorbed sugar, suggesting utilization in the gut wall. The method developed, using Doppler shift principle to measure blood flow and portal-carotid concentration differences, is suitable for obtaining quantitative determinations of net absorption of nutrients from the gastrointestinal tract of ruminants in a normal environment.