Determination of ileal digestible and apparent metabolizable energy contents of expeller-extracted and solvent-extracted canola meals for broiler chickens by the regression method

The present study was conducted to determine ileal digestible energy (IDE), metabolizable energy (ME), and nitrogen-corrected ME (ME_n) contents of expeller- (EECM) and solvent-extracted canola meal (SECM) for broiler chickens using the regression method. Dietary treatments consisted of a corn–soybean meal reference diet and four assay diets prepared by supplementing the reference diet with each of canola meals (EECM or SECM) at 100 or 200 g/kg, respectively, to partly replace the energy yielding sources in the reference diet. Birds received a standard starter diet from day 0 to 14 and the assay diets from day 14 to 21. On day 14, a total of 240 birds were grouped into eight blocks by body weight and randomly allocated to five dietary treatments in each block with six birds per cage in a randomized complete block design. Excreta samples were collected from day 18 to 20 and ileal digesta were collected on day 21. The IDE, ME, and ME_n (kcal/kg DM) of EECM or SECM were derived from the regression of EECM- or SECM-associated IDE, ME and ME_n intake (Y, kcal) against the intake of EECM or SECM (X, kg DM), respectively. Regression equations of IDE, ME and ME_n for the EECM-substituted diet were Y = −21.2 + 3035X (r² = 0.946), Y = −1.0 + 2807X (r² = 0.884) and Y = −2.0 + 2679X (r² = 0.902), respectively. The respective equations for the SECM diet were Y = 20.7 + 2881X (r² = 0.962), Y = 27.2 + 2077X (r² = 0.875) and Y = 24.7 + 2013X (r² = 0.901). The slope for IDE did not differ between the EECM and SECM whereas the slopes for ME and ME_n were greater (P < 0.05) for the EECM than for the SECM. These results indicate that the EECM might be a superior energy source for broiler chickens compared with the SECM when both canola meals are used to reduce the cost of feeding.