A technique for monitoring nutrient absorption in the conscious, unrestrained pig.

A surgical preparation allowing for the determination of apparent absorption in the conscious, unrestrained pig is described. The technique allows the collection of blood from the hepatic portal vein and vena cava, as well as the simultaneous determination of rate of flow through the portal vessel. A chronic electromagnetic blood flow probe is placed around, and a mechanical, hydraulically activated sampling needle attached to, the hepatic portal vein. An indwelling catheter is placed within the vena cava. By simultaneously determining nutrient concentration of hepatic portal and vena cava blood and then multiplying their difference by the rate of blood flow through the hepatic portal vein, one can make a point-in-time estimate of apparent absorption from the gastrointestinal tract.