Net energy content of dry extruded-expelled soybean meal fed with or without enzyme supplementation to growing pigs as determined by indirect calorimetry

Two experiments were conducted to determine the NE content of dry extruded-expelled soybean (DESBM) and the effect of a multienzyme carbohydrase (MC) mixture on the NE content of DESBM and to determine the effect of diet design on NE values in growing pigs using indirect calorimetry (IC). In Exp. 1, 24 barrows (19.6 +/- 0.51 kg BW) were allotted in a completely randomized design to 4 dietary treatments: a corn-soybean meal basal diet (Diet A), a diet containing Diet A and DESBM in an 80: 20 ratio with a constant CP (Diet B), a diet with an 80: 20 ratio of Diet A and DESBM with a constant corn: soybean meal ratio (Diet C), and a diet with simple substitution of Diet A with DESBM in an 80: 20 ratio (Diet D). Pigs were fed in metabolism crates for a period of 16 d to determine the DE and ME and thereafter were moved into an indirect calorimeter where O-2 consumption and CO2 production were measured to determine heat production and fasting heat production. The NE content of DESBM was calculated (difference method) to be 2,632, 2,548 and 2,540 kcal/kg DM in diets B, C, and D, respectively. Respective values obtained with published prediction equations were 2,624, 2,530 and 2,436 kcal/kg. In Exp. 2, 24 barrows (16.9 +/- 0.76 kg BW) were randomly allotted to 1 of 4 treatments. The diets were a corn-soybean meal basal diet and a diet containing the basal diet and DESBM in an 80: 20 ratio with a constant corn: soybean meal ratio with or without 2 levels (0.05% and 0.1%) of MC. The experimental procedures were similar to those described in Exp. 1. Enzyme supplementation improved (P < 0.0001) the DE, ME, and NE content of the DESBM. Multienzyme carbohydrase at 0.05% and 0.1% of the diet improved NE values of DESBM by 4.9% and 3.7%, respectively. In conclusion, the NE values of DESBM obtained with the IC method were higher than the values obtained with prediction equations; the disparity was least when diets were formulated with a constant CP level. However, as the difference method was used to determine the NE of ingredient, it is more appropriate to maintain a constant ratio between the ingredients. Also, the NE value of DESBM obtained for diets C and D were not different. Hence, the average NE value of DESBM evaluated was 2,544 kcal/kg DM. Enzyme supplementation improved the NE content of DESBM fed to growing pigs.