Apparent metabolizable energy value of expeller-extracted canola meal subjected to different processing conditions for growing broiler chickens

The objective of this study was to investigate the effect of processing conditions and chemical composition on ileal digestible energy (IDE), AME, and AMEn of 6 expeller-extracted canola meal (ECM) samples subjected to conditioning temperature at 90, 95, or 100°C and high or low screw torque over the second presses in a 3 × 2 factorial arrangement. The ECM samples were incorporated into a corn-soybean meal reference diet at 30% by replacing energy-yielding ingredients. A total of 210 one-day-old male broiler chicks (Ross 308) were fed common starter and grower diets until d 18, and then assigned to 7 experimental diets replicated 6 times, with 5 chicks per cage. After a 5-d diet acclimation period from d 18 to 22, excreta was collected for 72 h. The difference method was used to determine AME, which was corrected to zero N balance to obtain AMEn. Medium seed conditioning temperature resulted in the highest IDE, AME, and AMEn compared with low or high temperature, and high screw torque resulted in higher energy utilization compared with low torque (P < 0.001). There was also an interaction (P < 0.001) between conditioning temperature and screw torque. For ECM subjected to low or medium conditioning temperature at low screw torque, IDE, AME, and AMEn values ranging from 2,137 to 2,705, 2,089 to 2,655, and 1,977 to 2,482 kcal/kg of DM, respectively, were obtained. The mean AMEn values were 2,260 kcal/kg of DM, indicating a 7% reduction compared with AME values. The AMEn values were negatively correlated with neutral detergent fiber (NDF; r = -0.93; P = 0.001) and NDIN (r = -0.87; P = 0.001). Stepwise regression to predict AMEn value resulted in the following equation: AMEn (kcal/kg of DM) = 3,397.8 + (-100.1 × NDF %) + (279.5 × ash %) + (-33.8 × ADF %) (R² = 0.91; SE = 61.9; P = 0.001). These results indicate that AMEn values vary markedly among ECM samples, and chemical constituents, especially the fiber components, may have a considerable effect on AMEn value.