Digestible energy of sorghum grain for pigs could be predicted using a computer-controlled simulated digestion system

Abstract Prediction equations for digestible energy (DE) of sorghum grains fed to pigs have been generated based on chemical composition in our study. However, an in vitro method mimicking gastrointestinal digestion of pigs is more applicable to predict DE of feed ingredients in practice. This study evaluated in vitro DE (IVDE) and digestibility of gross energy (GE) in 28 samples of sorghum grain with a wide range in nutrient profiles using a 3-step computer-controlled simulated digestion system (CCSDS) and generated prediction equations based on IVDE and in vitro GE disappearance (IVGED) for previously determined DE and apparent total tract digestibility (ATTD) of GE. The IVDE (3305–4068 kcal/kg), IVDE/GE (0.72–0.91), IVGED (0.72–0.90), and in vitro dry matter (DM) disappearance (0.73–0.89; IVDMD) were quite variable and had a high negative correlation with tannin content in sorghum grain (r ≤ −0.90, P r  = 0.97 or 0.96, both P R 2  = 0.93, RMSE  = 40.9 kcal/kg, P R 2  = 0.92, RMSE = 0.01, P r  = 0.95 and 0.93, respectively, both P R 2  = 0.90, RMSE = 0.01, P R 2  = 0.87, RMSE = 0.01, P