Start Date: Jun 01, 2010
End Date: Jul 01, 2012
Obj. 1: Four different lipid sources (2 animal fats and 2 vegetable oils) will be selected based on degree of saturation. The nutrient balance experiment consists of utilizing 72 barrows weighing approximately 20 kg, which will be randomly assigned to 1 of 9 dietary treatments. The basal diet will be formulated to satisfy the nutrient requirements as suggested by the NRC (1998). Additional diets will consist of supplementing 10% of each lipid on top of the basal diet. Test diets will consist of both normal and oxidized samples of lipid, consisting of: poultry fat (an unsaturated animal fat), tallow (a saturated animal fat), corn oil (an unsaturated vegetable oil with a high content of linoleic acid), and canola oil (an unsaturated vegetable oil with a low content of linoleic acid). Obj. 2: Oxidation of lipid sources will be achieved by heating an aliquot of each oil at 190°C for 6 hours with compressed air at room temperature (22-24°C) bubbled into the sample at a flow rate of 97 cm 3/min. Pigs will be fed their respective experimental diets twice daily at an amount equivalent to approximately 4% of their body weight and will be provided ad libitum access to water. Pigs will be housed individually in metabolism crates designed for total, but separate collection of feces and urine. Pigs will be allowed to adapt to the experimental diets for 28 days followed by a 4-day total collection period. At the end of the collection period, all pigs will be fasted for 24 hours and urine will be collected to determine the concentration of polar and non-polar secondary oxidation products to determine in vivo production of secondary oxidation products. Urine 4-HNE concentrations normalized to urine creatinine concentrations and serum concentrations of TBARS will be measured as indicators of oxidative stress. Energy and nitrogen concentrations will be determined by adiabatic bomb calorimetry and thermo combustion, respectively, and nutrient balance and DE and ME determinations will be calculated. Obj. 3: On the final day of the experiment for Objective 2, the impact of dietary fat source and fat oxidation on intestinal barrier function will be determined by administering an oral dose of a cocktail containing 10 grams of lactulose and 2 grams of mannitol to all pigs. Urine will be collected for a period of 6 hours into a container with chlorhexidine to prevent microbial contamination. Urinary concentrations of lactulose and mannitol will be determined by HPLC, and the lactulose:mannitol ratio will be calculated as an indicator of small intestinal permeability. Blood samples will be collected from each pig, and serum concentrations of endotoxin will be determined by the fluorescent PyroGene® rFC assay as another indicator of intestinal barrier function. Blood samples will be collected after an overnight fast and at 3 hours after feeding for determination of endotoxin in both the fasted and fed state. Serum a-1- acid glycoprotein and haptoglobin concentrations will be measured as indicators of systemic inflammation. Fecal concentrations of IgA will be determined on freshly collected and frozen fecal samples as a marker of mucosal immunity.