Evaluation of Collection Method and Diet Effects on Apparent Digestibility and Energy Values of Swine Diets

Two experiments were conducted to investigate the effects of collection method and diet on estimating digestibility values. In Exp. 1, 24 barrows were fed either a corn-soybean meal diet (CSBM) or CSBM with 20% dried distillers grains with solubles (DDGS). Fecal collections were based on exact timing (Day collection) or marker-to-marker collection (MM) methods during a 4-d period. Diets contained 0.5% of titanium dioxide (TiO2) for estimating digestibility using the index method. In Exp. 2, the effects of collection method and basal diet on determination of DDGS digestibility were studied using 24 barrows. Diets were CSBM (basal 1), barley-canola meal diet (BCM; basal 2), and 20% of basal 1 or basal 2 replaced by DDGS (total 1 and total 2). Day and MM methods were administered for each individual pig by separate collections and measurements of feces. In Exp. 1, Day and MM methods were not different (P \u3e 0.10) on estimation of digestibility values, except that ME values tended to be greater (0.05 \u3c P \u3c 0.10) when estimated using Day vs. MM methods; whereas, digestibility estimates and dietary energy values were about 0.5% and 20 kcal/kg lower (P \u3c 0.05) estimated using the index vs. total collection (Day and MM) methods. In Exp. 2, digestibility estimates of diets and DDGS were not different (P \u3e 0.10) calculated using Day and MM methods. The average DE and ME (kcal/kg, as-fed) of DDGS were 4,035 and 3,704, respectively estimated using basal 1, which were not different (P \u3e 0.10) from using basal 2 (4,081 and 3,651, respectively). In conclusion, digestibility values of a complex diet and DDGS are not different when estimated by Day or MM method. When corn-soybean meal based diets are fed, digestibility estimates are lower using the index method compared to the total collection method. Additionally, basal diets may not affect DDGS digestibility estimates. Advisors: Phillip S. Miller and Thomas E. Burke