The aim of this study was to evaluate the effects of two species of poultry (cockerel and Japanese quail), two levels of enzyme (0 and 0.5 g/kg), and 6 processing methods (control (C), gamma irradiation 25 (GI25), and 50 kGy (GI50), autoclaving (AU), fermentation without lactobacillus (F), and fermentation with lactobacillus (FL)) on the nitrogen-corrected apparent metabolizable energy (AMEn) of barley. In this experiment, each processing method was tested at two levels of enzyme (0 and 0.5 g/kg) in six replications with two cockerels or four quails per replication. The results showed that the AMEn values by barley processing methods were: C-11.45 and 12.27; GI25–11.50 and 11.30; GI50–11.49 and 11.29; AU-11.70 and 11.46; F-12.90 and 12.30; FL-1295 and 12.51 MJ/kg in cockerels and quails, respectively. The AMEn (11.49 MJ/kg) of enzyme 0 was significantly lower than that of enzyme 0.5 (12.35 MJ/kg). There was a significant difference in the AMEn of processed barley between cockerels and quails. In conclusion, the most effective processing method of barley for AMEn is fermentation with lactobacillus and enzyme.