Approaches for quantifying gastrointestinal nutrient absorption and metabolism in a native and a modern pig breed

Abstract

SUMMARYWhen working with multi-catheterized animals, success and failure are separated by surgical procedures and minor details in catheter design and care. The current paper is a detailed description of novel approaches to multi-catheterization of pigs for investigations into nutrient absorption and metabolism of portal-drained viscera (PDV) in a native obese (Iberian) and a modern (Landrace) breed. Three Iberian and three Landrace gilts (25 kg average body weight; BW) were fitted with catheters in the carotid artery (CA), the portal vein (PV) and the ileal vein (IV). Tygon rings were attached to the catheter to mark the extent of introduction into the vessel and facilitate its fixing by means of a non-absorbable suture. The PV was catheterized through the visceral side of the left-lateral lobe of the liver and IV through a branch of the vein. The CA was secured directly in place with a purse-string suture where the artery was not occluded. Patency of the catheters was checked weekly and catheters filled with sterile heparinized saline and closed by two knots. Portal blood flow was determined to test the procedures. A 15 ml pulse dose of para-aminohippuric acid (PAH; 2% w/v) was infused into IV 45 min prior to blood sampling, followed by continuous infusion of 0·8 ml/min. Blood samples (4·5 ml) were taken simultaneously from CA and PV, using heparinized tubes, 5 min before feeding 0·25 of the total daily ration (barley–soybean meal diet; 160 g crude protein (CP)/kg; 14–14·5 MJ metabolizable energy (ME)/kg dry matter (DM); 2·4×ME for maintenance), and every 30 min for 4 h and then hourly until 6 h after feeding. Blood was centrifuged and plasma harvested and stored at −20 °C until PAH analysis. Whole-blood flow was based on the Fick principle. Post-prandial PDV blood flow was lower for the Iberian pigs than Landrace (866 and 1464 ml/min, respectively). The concurrence of access to the PV through the liver with a minimal wound, the non-occluded blood flow in CA, and the catheter design and care were all critical for the fast recovery of pigs and catheter patency. The procedures followed are recommended for studies of absorption of nutrients from the gastrointestinal tract and the impact of PDV on the metabolism of conscious, unrestrained, growing pigs.