Comparison of Energy Values Estimated by Direct and Indirect Methods for Broiler Chickens

Abstract

Objective: The objective of this study was to compare energy values of wheat or barley derived from the direct and regression methods for broiler chickens. Materials and Methods: Seven diets consisted of a corn-soybean meal-based basal diet, 2 semi-purified diets mixed to contain wheat or barley as the sole source of energy and 4 test diets prepared by supplementing the basal diet with wheat or barley at 15 or 30%, respectively. Chromic oxide was used as an indigestible index to calculate the metabolizability. A total of 504 21-days-old male Ross 308 broiler chickens were allocated based on body weight into 7 treatments with 6 replicate cages and 12 birds per cage by using a randomized complete block design. From d 21, birds were fed the experimental diets for 5-d and excreta samples were collected from d 24-26. Results: The apparent metabolizable energy (AME) of the wheat using the direct method (2,934 kcal kg^–1 DM) was not different from the value (3,026 kcal kg^–1 DM) derived from the regression method. However, the AME of barley obtained from the direct method (2,730 kcal kg^–1 DM) differed from the value (2,970 kcal kg^–1 DM) measured by the regression method. Conclusion: The direct and regression methods gave different estimates of the AME in barley but not in wheat fed to broiler chickens.