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

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Abstract
The Doppler ultrasonic blood flow system was employed to measure the portal blood flow rate (mean 40.9 m./min/kg) in 7 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 evironment The mean velocity of portal flow 1 hr. postprandial was increased 9.7% by feeding. The net absorption of total sugars and glucose determined from plots of portal-carotid concentration differences over the 12-hr. 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. The difference between the total sugars and glucose absorbed indicates that some galactose or lactose per se is absorbed. The method developed in this study is suitable for obtaining quantitative determinations of net absorption of nutrients from the gastrointestinal tract of ruminants in a normal environment.