Determination and prediction of digestible and metabolizable energy of soybean meal and wheat bran for finishing pigs

• Equation predictions of digestible and metabolizable energy of soybean meal and wheat bran for finishing pig are proposed. • Fiber compositions are negatively correlated with the digestible and metabolizable energy of soybean meal. • The chemical composition of soybean meal and wheat bran are considerably different in the regions of production. The objective of this study was to determine the chemical composition, digestible energy (DE) and metabolizable energy (ME) in soybean meal (SBM) and wheat bran (WB) fed to finishing pigs and to develop regression equations for predicting DE and ME of SBM and WB. Ten SBM samples were obtained from nine different crushing facilities in nine provinces in China. Ten WB samples were collected from different feed mills of China. There were 2 separated experiments per ingredient in this study, and each experiment was conducted as 6 × 6 Latin Square design with 6 pigs, 6 diets, and 6 periods for determining the DE and ME in SBM and WB. Same basal diets and 5 corn-SBM or 5 corn-SBM-WB diets were included in each Latin Square design, which were allotted to two 6 × 6 Latin Square design. There were differences ( P < 0.05) in the DE and ME values in different sources of SBM and WB, respectively. The best-fit equations for SBM were DE (kcal/kg DM) = 298.73 – (63.30 ×% Ash) – (40.60 ×% EE) – (13.84 ×% NDF) + (0.98 × GE (kcal/kg DM)) ( R 2 = 0.87, P = 0.02) and ME (kcal/kg DM) = 244.67 – (66.82 ×% Ash) – (50.65 ×% EE) – (14.85 ×% NDF) + (0.96 ×GE (kcal/kg DM)) ( R 2 = 0.92, P < 0.01). The best-fit equations for WB were DE (kcal/kg DM) = – 1864.46 + (220.80 ×% CP) + (56.31 ×% Ash) – (61.95 ×% ADF) + (24.08 ×% SCHO) ( R 2 = 0.90, P < 0.01) and ME (kcal/kg DM) = 522.87 + (184.78 ×% CP) + (25.00 ×% Ash) – (20.45 ×% NDF) – (62.43 ×% ADF) ( R 2 = 0.92, P < 0.01). All independent variables are on the DM basis. The chemical composition of SBM and WB vary substantially among originating regions, resulting in considerable variation in its available energy value for pigs. A series of regression equations were developed in the present study to estimate the DE and ME of commercially available SBM and WB for finishing pigs.