Net energy of diets containing wheat-corn distillers dried grains with solubles as determined by indirect calorimetry, comparative slaughter, and chemical composition methods

The NE content of diets containing wheat-corn distillers dried grains with solubles (wcDDGS; 1: 1 ratio) fed to growing pigs was determined using the comparative slaughter (CS), indirect calorimetry (IC), and chemical composition (CH) methods. The experimental diets were a corn-soybean meal control diet (CTRL), CTRL + 15% wcDDGS, and CTRL + 30% wcDDGS. In Exp. 1, 56 barrows (18.5 kg BW) were used to determine the NE value of diets using the CS method. Pigs were initially placed in 8 groups (7/group), based on BW and 1 pig/group was killed at the start of the experiment to obtain baseline body composition. The remaining 48 pigs were housed in pairs and allotted to the 3 diets (n = 8). Pigs had free access to feed and water for a 28-d period, after which 1 pig/pen was slaughtered to determine final body composition. Based on the CS method, NE values of 2,430, 2,427, and 2,429 kcal/kg DM were obtained for diets containing 0%, 15%, and 30% wcDDGS, respectively. In Exp. 2, 18 barrows (20.4 kg BW) were used to determine the NE value of diets using the IC and CH methods. Pigs were individually housed in metabolism crates and fed the 3 diets (n = 6) at 550 kcal ME/kg BW/d for a 16-d period. Feces and urine were collected from d 11 to 16, followed by measurement of O-2 consumption, CO2 production, and urinary N, over a 36-h period using an IC system. For the IC method, NE values of 2,586, 2,513, and 2,520 kcal/kg DM were obtained for diets containing 0%, 15%, and 30% wcDDGS, respectively, and corresponding values for the CH method were 2,447, 2,451, and 2,368 kcal/kg DM, respectively. The NE values that were obtained with the CS, IC, and CH methods were not different.