A computer-controlled simulated digestion system is a promising in vitro digestibility technique to predict 'digestible energy of corn grain for growing pigs

An equation for digestible energy (DE) of corn grain fed to pigs has been established based on chemical composition or near-infrared reflectance spectroscopy in our laboratory. And an in vitro digestibility technique to predict the DE value of feed ingredients is also applicable in practice. This study was conducted to evaluate the in vitro digestible energy (IVDE) and digestibility of gross energy (GE) in 13 selected samples of corn grain with a wide range in nutrient profiles using a computer-controlled simulated digestion system (CCSDS) and to generate prediction equations based on IVDE and IVDE/GE values for previously determined DE and digestibility of GE (DE/GE). Among the 13 samples, starch, DE and DE/GE content (dry matter basis) ranged from 603 to 662 g/kg, 3843 to 4068 kcal/kg, and 0.89 to 0.94, respectively. The IVDE (3440-3637 kcal/kg) or IVDE/GE (0.80-0.84) showed a similar variation tendency with the DE or DE/GE value in the corn grains. There were highly positive correlations between IVDE and determined DE (r = 0.99, P < 0.01) and between IVDE/GE and determined DE/GE (r = 0.98, P < 0.01). Linear relationships were observed in the 13 corn samples: DE = L14 x IVDE 89.56 (R-2 = 0.97, P < 0.01) and DE/GE = 1.12 x IVDE/GE 0.18 (R-2 = 0.97, P < 0.01). All samples showed the differences of less than 25 kcal/kg between observed and predicted DE and less than 0.005 between observed and predicted DE/GE. The slopes and R-2 for the linear relationship between observed and predicted values were both 1 and 0.97. Overall, CCSDS is a promising in vitro digestibility technique to predict DE and digestibility of GE in corn gain for pigs.