True ileal protein and amino acid digestibilities in wheat dried distillers’ grains with solubles fed to finishing pigs

As wheat dried distillers’ grains with solubles (WDDGS) become increasingly available in western Canada, there is currently a great interest in evaluating its potential as a feedstuff for pigs. Thus, the apparent, standardized and true ileal crude protein (CP) and amino acid (AA) digestibilities in WDDGS were determined. Six finishing pigs (∼82 kg initial BW) fitted with a simple T-cannula at the distal ileum were fed diets containing either 400 g/kg WDDGS or 50 g/kg casein as the sole protein source in a simple crossover design. Chromic oxide (3 g/kg) and acid insoluble ash (AIA, 10 g/kg) were included in the diets as indigestible markers. The casein diet was used to quantify endogenous protein and AA losses. Standardized ileal CP and AA digestibilities were estimated using published basal endogenous protein and AA losses. Pigs were acclimatized to their diets for 5 days followed by a continuous 12-h digesta collection period on days 6 and 7. Ileal CP and AA digestibility coefficients obtained with AIA as a marker were similar to those obtained with Cr2O3 (P>0.05). Endogenous losses, coefficient of apparent ileal digestibility and coefficient of true ileal digestibility in g/kg dry matter intake were 22.81, 0.64 and 0.79 for CP, 0.94, 0.73 and 0.89 for arginine, 0.41, 0.68 and 0.79 for histidine, 0.46, 0.73 and 0.81 for isoleucine, 0.59, 0.78 and 0.83 for leucine, 0.54, 0.36 and 0.56 for lysine, 0.10, 0.71 and 0.77 for methionine, 0.32, 0.82 and 0.86 for phenylalanine, 0.89, 0.62 and 0.78 for threonine and 0.59, 0.71 and 0.79 for valine. Of all the essential AA analyzed, lysine had the lowest digestibility value, which suggests reduced availability of this AA.