تعیین ترکیب شیمیایی و انرژی قابل سوخت و ساز ظاهری و حقیقی ارقام مختلف جو در جوجه‌های گوشتی

This study was conducted to determine chemical composition and evaluated apparent metabolisable energy (AME) and true metabolisable energy (TME) values of five Iranian barley cultivars. Basal diet contained corn soybean and in each of the test diets barley was substituted for 30% of corn and soybean fractions. The study was carried out in 3 experiments. In experiment 1, metabolisable energy (ME) values were measured by both total collection and markers (chromic oxide) in excreta of 35-d-old chicks. In experiment 2, ME values of the barley cultivars were determined by ileal digesta procedure. In experiment 3, 36 48-d-old broiler chicks (used in experiment 1 and 2) were used to determine TME and the nitrogen corrected TME (TMEn) of the barley cultivars. Highly significant differences (P<0.05) between bioassay methods were observed on average barley ME values. The average barley AMEn value measured by ileal digesta method was significantly (P<0.05) higher than excreta (total collection and markers in excreta) (2716 Vs. 2318 and 2124 kcal/kg, respectively). Barley ME values were influenced by cultivar (P<0.05) and the hullless cultivar showed greater AME value than the hulled cultivars (2695 vs. 2407.5 kcal/kg AME 2630 vs. 2324.7 kcal/kg AMEn). Cultivar had no significant effect on barley TME value. It was concluded that there is high variation between energy contents of Iranian barley cultivars. In addition, ileal digesta was found not to be an accurate bioassay for determination of barley AME value in broiler chicks.