Differences in AME and IDE were found between diets without and with exogenous protease (P < 0.01) with values of 12.79 MJ/kg and 13.22 MJ/kg for semi-purified diets without protease and 13.22 MJ/kg and 13.46 MJ/kg with protease, respectively. In the present study, AME and IDE were improved (P < 0.01) by 0.43 and 0.51 MJ/kg, respectively when protease was supplemented.