The TMEn values of two barley samples and a corn sample with and without enzyme addition were determined in an experiment conducted over two consecutive weekly periods. Adult roosters were not influenced by the high beta-glucan content of Scout barley, which had a higher energy value (3.70 kcal/g DM) than the Bedford barley (3.44 kcal/g DM). Overall the energy value of the grain increased 3% due to enzyme supplementation. The 48-h excreta collection time was considered to be adequate for TMEn determination.