Digestible Energy, ME, and DM and CP Digestibility Values of Dried Distillers Grains with Solubles (DDGS) Estimated from Corn-soybean Meal or Barley-canola Meal Basal Diets and Using Different Collection Methods

Abstract Text: To determine the effects of collection method and basal diet on estimating digestibility of DDGS, 24 barrows in 2 replicates (BW = 90.3 and 90.9 kg, respectively) were individually fed 1 of 4 diets: corn-soybean meal (CSBM, basal-1), barley-canola meal (BCM, basal-2), and 20% of basal-1 or basal-2 replaced by DDGS (10% EE; total-1 and total-2). Time-based (Day) and marker-to-marker (MM) collection methods were employed for each pig using separated fecal collections. Diets contained 0.5% titanium dioxide (TiO₂) to estimate digestibility using the index method (IN). Data were analyzed as a 4 × 3 or 2 × 3 factorial in a split-plot design for comparisons of diet or DDGS digestibility, respectively. There were interactions (P < 0.05) for estimating dietary digestibility between diet and method for all variables. The apparent total tract digestibility (ATTD) of DM and CP, DE and ME were not affected (P > 0.10) by method in CSBM-based diets. However, for the basal-2 diet, all estimates were greater (P < 0.05) when calculated using Day vs. MM or IN. Using the MM method, the ATTD of DM and CP were greater (P < 0.05) than IN, and DE and ME tended to be greater (P < 0.10) using MM vs. IN. For the total-2 diet, all estimates calculated using Day and MM were not different (P > 0.10) and were greater (P < 0.05) than those using IN. Digestibility estimates of DDGS were not affected (P > 0.10) by basal diet. The ATTD of DM, DE (%), and ME (kcal/kg) of DDGS using MM were greater (P < 0.05) than IN, and ATTD of CP tended to be greater (P < 0.10) using MM vs. IN; whereas, estimates using the Day method were not different (P > 0.10) from MM or IN. Digestible energy (kcal/kg) of DDGS was greater (P < 0.05) using Day or MM vs. IN. The mean DE and ME (DM basis) of DDGS were 4,374 and 4,037, and 4,215 and 3,884 kcal/kg estimated using basal-1 and basal-2 diets, respectively. In conclusion, digestibility estimates of BCM-based diets and DDGS were lower using IN vs. total collection (Day and MM) methods. Except for basal BCM diet, digestibility estimates for DDGS and complete diets were not different using Day and MM methods. Basal diet does not appear to affect digestibility estimates of DDGS.

Keywords: collection method, digestibility, pig