The objective of this study was to assess NDF digestibility and energy content of canola meals (CM) produced in Canada over a 4-year period. Canola meal samples were collected from 12 Canadian crushing plants over 4 years (total = 48) and analyzed for chemical composition, potentially digestible NDF (pdNDF), total digestible nutrients at maintenance (TDN_1x), and NEL simulating a cow consuming 3× maintenance (NEL_3x). To estimate TDN_1x and NEL_3x, pdNDF was calculated as: (1) pdNDF_OBS = (NDF − NDICP − iNDF), using observed CM iNDF values after 288-h in situ ruminal incubations; (2) pdNDF_NRC = (NDF − NDICP − ADL) × {1 − [ADL/(NDF − NDICP)]^0.667}, according to NRC 2001; (3) pdNDF_CNCPS = (NDF − NDICP − iNDF), according to the CNCPS that calculates iNDF as acid detergent lignin (ADL) × 2.4. Concentrations of NDF, NDICP, and ADL in all equations were given in % of DM. Truly digestible NDF was estimated multiplying the observed and predicted pdNDF by 0.75. Then TDN_1x and NEL_3x were calculated assuming a diet with 74% of TDN_1x according to NRC 2001 equations. Regressions of predicted (NRC or CNCPS) vs. observed values were performed using Proc Reg of SAS (Table 1). pdNDF_OBS, pdNDF_NRC, and pdNDF_CNCPS averaged 15, 8, and 2.4% of DM, respectively. The TDN_1x average were 73, 67, and 64%, respectively. The NEL_3x average were 1.88, 1.73, and 1.63 Mcal/kg, and ranged from 1.73 to 2.08; 1.51 to 1.94; and 1.4 to 1.87 Mcal/kg DM for NEL_3xOBS, NEL_3xNRC, and NEL_3xCNCPS, respectively. Our results indicate that NEL_3x from CM diets may be underestimated in current nutritional models due to underestimations in CM NDF digestibility. More accurate information on CM NDF digestibility may improve energy content estimation, thus improving diet formulation accuracy. Table 1.

Item	Intercept	SE	Slope	SE	P-valueslope	R2	RMSE
pdNDFNRC	7.46	1.79	−0.01	0.12	0.91	0.00	2.00
pdNDFCNCPS	−5.61	3.61	0.54	0.24	0.03	0.10	4.00
iNDFNRC	14.4	1.72	0.27	0.18	0.14	0.05	1.96
iNDFCNCPS	17.3	3.61	0.48	0.38	0.21	0.04	4.10
TDN1xNRC	2.18	6.54	0.89	0.09	<0.01	0.70	1.65
TDN1xCNCPS	−9.20	11.9	1.00	0.16	<0.01	0.47	3.02
NEL3xNRC	−0.06	0.18	0.95	0.09	<0.01	0.70	0.04
NEL3xCNCPS	−0.46	0.32	1.11	0.17	<0.01	0.50	0.08