Technical note: An improved surgical model for the long-term studies of kinetics and quantification of nutrient absorption in swine1,2

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An improved technique to study kinetics and quantitative absorption of nutrients in pigs is described. Three female pigs (35 kg of BW) were surgically modified with catheters in the hepatic portal vein and carotid artery and an ultrasonic flow probe around the portal vein. Catheter placement and patency was secured using distal modifications (rings and holes) and nonabsorbable suture. Catheters and flow probe cable were tunneled subcutaneously after exteriorization for further protection. Fibrosis and adhesions in the body cavity were minimized by avoiding excessive manipulation and drying of viscera. Pigs were supported during recovery by intravenous fluid therapy of AA and electrolytes until regular feeding resumed. Catheters were flushed daily with heparinized saline (200 IU/L). After 10 d, pigs were fed a diet based on wheat and soybean meal for 6 consecutive 7-d periods. On d 7, blood was collected postprandially every 15 min from -15 to 60 min, 30 to 240 min, 60 to 480 min, and 120 to 720 min. Blood flow was measured simultaneously. Plasma was analyzed for glucose, and net glucose absorption was calculated from plasma portal-arterial differences x plasma flow [blood flow x (1 - hematocrit)]. The specific improvements for long-term use of this model are distal modifications of the catheters, postoperative treatment using parental nutrition and gut motility drug, prevention of infection of body cavity by further tunneling of catheters and blood flow probe cable, and use of ultrasonic blood flow probes and meter. Blood flow measurements using an ultrasonic blood flow probe was not changed after 52 d compared with 10 d post-surgery, indicating the reliability of this model. This catheterized pig model, thus, will allow the long-term study of the kinetics of nutrient absorption.