108 Estimating net energy of soybean meal for 47 to 110 kg growing pigs using a growth assay

Abstract The NE of SBM for growing pigs with body weight (BW) from 47 to 110 kg was determined in the current study using the growth assay. In the first study, a total of 826 pigs (B =, 46.8 ± 2.5 kg) in 44 pens (18 to 19 pigs per pen, 11 pens per treatment) were randomly allotted into one of 4 dietary treatments with initial BW and sex as blocks for 21 d: Corn-SBM based diets with 29.0, 25.7, 22.3, or 19.0% of SBM. Compared with the first study, the second study was conducted with a total of 820 pigs at greater BW (67.0 ± 3.4 kg). Pens were randomly allotted into one of 4 dietary treatments for 42 d: Corn-SBM based diet with 29.0, 25.0, 21.0, or 17.0% of SBM. NE of corn 2,674 kcal/kg, as fed basis, dry matter (DM) 87.1% was calculated according to NRC (2012) and determined with the analyzed nutrient composition. SBM used in both experiments contained 89.4% of DM, 46.6% of CP, 5.9% of starch, 1.6% of EE, 8.5% of NDF, 6.3% of ADF, and 6.1% of ash. The reduced level of SBM was replaced with corn and crystalline amino acids. Data were analyzed by linear and quadratic contrasts using the Proc MIXED of SAS. In the early growing phase (47 to 67 kg), increasing SBM levels from 19.0 to 29.0% tended to linearly decrease average daily feed intake (ADFI; Linear, P = 0.081, 2.09, 2.03, 2.03, and 2.00 kg/d) but did not affect average daily gain (ADG) or final BW. On the contrary, increasing SBM levels decreased ADG and ADFI in pigs growing from 67 to 110 kg (linear, P 0.05, ADG: 1.03, 1.02, 1.01, and 1.00 kg/d; ADFI: 2.72, 2,64, 2.63, and 2.58 kg/d). Linear regression analysis showed that, to maintain calorie efficiency, the estimated NE of SBM for pigs growing from 47 to 67 kg is 3,000 kcal/kg (as fed basis), which is 1.12 times corn NE. The estimated NE of SBM for pigs growing from 67 to 110 kg is 2,705 kcal/kg (as fed basis), which is 1.01 times corn NE. Taken together, the results suggest that NE of SBM is close to or greater than NE of corn, warranting the necessity to evaluate the energy of feed ingredients in pigs growing in different phases. The predicting equation of SBM NE (Eq. 1-3 and 1-8, NRC 2012) is recommended to be modified by timing a coefficient of 1.36 or 1.19 for early- or late-growing pigs, respectively, according to the NE of SBM calculated from growth performance data in this study.