<strong>Digestive</strong> <strong>Physiology</strong> <strong>of</strong> <strong>Pigs</strong> 3041 Development and validation <strong>of</strong> a spectroscopy method to predict protein digestibility. L. F. Wang* 1 , M. L. Swift 1,2 , and R. T. Zijlstra 1 , 1 University <strong>of</strong> Alberta, Edmonton, AB, Canada, 2 Alberta Agriculture and Rural Development, Lacombe, AB, Canada. Protein digestibility is traditionally measured by chemical analyses <strong>of</strong> protein and marker concentration in digesta and diets. Potentially, protein digestibility can also be predicted by marker concentrations and spectral analyses <strong>of</strong> digesta and diets. Spectroscopy is a rapid, non-destructive method to ascertain qualitative and quantitative chemical information. Based on Beer’s law, a spectroscopic method was developed to predict in vivo protein digestibility. Thus, 411 samples <strong>of</strong> digesta and diets from 7 feedstuffs with predetermined apparent ileal digestibility (AID) <strong>of</strong> protein were scanned on a Fourier transform mid-infrared instrument with a singlereflection attenuated total reflectance attachment. The AID <strong>of</strong> protein was calculated from peak intensities <strong>of</strong> spectra and measured marker concentrations in digesta and diets, and then compared with in vivo AID <strong>of</strong> protein. The AID <strong>of</strong> protein <strong>of</strong> wheat-based diets was predicted accurately with a deviation <strong>of</strong> 0.68 ± 0.86% from in vivo AID ranging from 60.4 to 87.8% in an in vivo trial. The calculated AID <strong>of</strong> protein based on the amide I peak at 1643 cm −1 best predicted (R 2 = 0.99) in vivo AID <strong>of</strong> protein. This peak is primarily induced by C = O stretching vibration (80%) plus C-N stretching. For feedstuffs mixed with N-free basal diet, accuracy was lower (R 2 = 0.72 to 0.91). Fine corn starch particles may cover the surface <strong>of</strong> dietary feedstuff particles causing increased absorbance <strong>of</strong> corn starch and decreased absorbance <strong>of</strong> feedstuff protein, resulting in lower calculated AID <strong>of</strong> protein. The R 2 between spectroscopy predictions and in vivo AID <strong>of</strong> protein was 0.91 for corn distillers dried grains with solubles (DDGS), 0.90 for wheat DDGS, 0.70 for blended DDGS, 0.90 for triticale DDGS, 0.72 for field pea and 0.83 for wheat millrun. In conclusion, instead <strong>of</strong> predictions based on calibration, protein digestibility can also be predicted directly from spectra. Key words: protein digestibility, pig, spectroscopy 3042 The in vivo infusion <strong>of</strong> hydrogen peroxide (H 2 O 2 ) induces oxidative stress in piglets and differentially <strong>XII</strong> INTERNATIONAL SYMPOSIUM ON DIGESTIVE PHYSIOLOGY OF PIGS 134 Session VI affects the activities <strong>of</strong> small intestinal carbohydrate digesting enzymes in pigs. D. Lackeyram,* Y. Mine, T. Archbold, and M. Fan, University <strong>of</strong> Guelph, Guelph, Ontario, Canada. Chronic fatigue syndrome (CFS) is characterized by persistent and relapsing fatigue that involves oxidative stress in its pathogenesis. We tested the hypothesis that decreases in key carbohydrate-digesting enzyme activities in the gut are one <strong>of</strong> the major biological mechanisms <strong>of</strong> developing CFS in liquid formula-fed piglets with in vivo infusion <strong>of</strong> H 2 O 2 . Piglets <strong>of</strong> 5 d <strong>of</strong> age were fitted with an intraperitoneal catheter and infused with either H 2 O 2 at 5 mmol/kg BW (PER, n = 8) or the same volume <strong>of</strong> saline (CON, n = 8) in 6 20-mL doses daily for a period <strong>of</strong> 10 d. During this time, animal behavior was monitored, blood samples taken and jejunal enzyme activity kinetic experiments for lactase, sucrase, maltase and maltaseglucoamylase were conducted. Plasma GSH levels remained similar (P > 0.05) to the pre-infusion level over the study duration in the CON group, whereas this was 65% lower (P < 0.05) than the pre-infusion level in the PER group. Piglets experiencing oxidative stress had lower (P < 0.05) physical mobility and reduced maximal specific activities for lactase (V max : PER, 6.54 ± 0.68 vs. CON, 12.65 ± 0.69) and maltase (PER, 57.39 ± 1.02 vs. CON, 75.6 ± 1.04 µmol/mg protein.min), respectively. However, there were no differences (P > 0.05) in the maximal specific activity <strong>of</strong> sucrase (PER, 10.50 ± 1.37 vs. CON, 12.40 ± 1.55 µmol/mg protein.min) and maltaseglucoamylase (V max : PER, 0.71 ± 0.08 vs. CON, 0.70 ± 0.07), respectively. We conclude that the infusion <strong>of</strong> a suitable dose <strong>of</strong> hydrogen peroxide induced chronic fatigue symptoms in piglets. In addition, oxidative stress in vivo differentially affected the maximal activities <strong>of</strong> key small intestinal carbohydrate-digesting enzymes. Dramatic decreases in gut mucosal lactase and maltase maximal activities in response to oxidative stress would lead to a reduced essential metabolic fuel availability to red blood cells and brain, contributing to the pathogenesis <strong>of</strong> CFS. Key words: chronic fatigue syndrome, digestive capacity, gut mucosal carbohydrate-digesting enzymes
<strong>Digestive</strong> <strong>Physiology</strong> <strong>of</strong> <strong>Pigs</strong> <strong>XII</strong> INTERNATIONAL SYMPOSIUM ON DIGESTIVE PHYSIOLOGY OF PIGS Session VII: Manipulation <strong>of</strong> Digestion 135 Session VII