Identifying dietary fiber components that best predict nutrient digestibility and energy content in 9 corn co-products fed to growing pigs

Abstract Text: An experiment was conducted to determine the best-fitting dietary fiber (DF) assay to estimate the effect of DF concentration and to predict the digestibility of energy, DF and AA of 9 corn co-products: conventional corn bran, corn bran with solubles, corn distillers dried grains with solubles (DDGS) conventionally produced, reduced oil DDGS, uncooked DDGS, high protein distillers dried grains, dehulled degermed corn, corn germ meal, and corn gluten meal. A total of 20 growing pigs (initial BW: 25.9 ± 2.5 kg) were fitted with a T-cannula in the distal ileum and allotted to 10 dietary treatment groups in a 4-period incomplete block design with 8 observations per treatment. Treatments included a corn soybean meal-based basal diet and 9 diets obtained by mixing 70% of the basal diet with 30% of the test ingredient. The 9 ingredients were analyzed for the concentration of NDF, TDF, total non-starch polysaccharides (NSP), and 5 constituent monosaccharides of NSP, namely arabinose (Ara), xylose (Xyl), mannose (Man), glucose (Glc), and galactose (Gal). The apparent ileal (AID) and total tract digestibility (ATTD) of GE, DM, NDF and the AID of AA of ingredients were measured. A single best fitting DF assay was assessed and ranked for each trait, showing that total NSP concentration best explained the variance of AID of GE (R²=0.65; cubic, P=0.02) and DM (R²=0.67; cubic, P=0.04). The xylose concentration in NSP best explained the variance in ATTD of GE (R²=0.80; cubic, P<0.01), DM (R²=0.78; cubic, P<0.01), and NDF (R²=0.63; cubic, P<0.01); AID of Met (R²=0.40; cubic, P=0.02), Met+Cys (R²=0.44; cubic, P=0.04), and Trp (R²=0.11; cubic, P=0.04); and DE (R²=0.66; linear, P=0.02) and ME (R²=0.71; cubic, P=0.01) values. The AID of Lys was not predictable (P > 0.05) from the DF concentration. In conclusion, the total NSP or xylose in NSP were the DF assays that best explained variation due to DF concentration, and with the exception of AID of Lys, can be used to explain digestibility traits and energy values in corn co-products.

Keywords: corn co-products, dietary fiber, digestibility, energy, pig