Three trials were conducted to determine the available energy of different wheat screening samples collected from different locations of Khorasan in Iran. In experiment 1, chemical composition and the nitrogen corrected true metabolisable energy (TMEn) were evaluated. A precision-fed rooster assay was used, in which, each wheat screening sample was tube fed to adult roosters, and the excreta were collected for 48 h. In exp. 2 and 3, 5 and 2 wheat screening samples-based diet with or without xylanase and phytase were fed to 16 d old battery reared chicks and total consumption and excreta were measured during 3 next days. The variable nature of wheat screening varieties led to significant differences in mean TMEn values (P < 0.01). The TMEn values of samples determined with adult roosters varied by ± 5.03% of the mean value (3097.65 ± 49.32 kcal/kg) and ranged from 2734.90 to 3245.12 kcal/kg. There was a significant correlation (P < 0.05) between chemical composition (CP, EE, ash and CF) and TMEn. The best equation for TMEn yielded an R2 = 0.86, with crude fiber being the most efficient compound. The average AMEn values of 5 and 2 samples determined with young broiler chickens were 2968.41 ± 25.70 kcal/kg and 2976.38 ± 8.34 kcal/kg in exp2 and exp3 respectively. Addition of xylanase and phytase to wheat screenings resulted in significant (P < 0.01) improvement in AMEn (4.21 and 2.92% respectively).

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