Formulating diets containing corn distillers dried grains with solubles on a net energy basis: Effects on pig performance and on energy and nutrient digestibility1

A field-scale study was conducted to determine whether formulating diets containing corn, soybean meal, soybean oil, and corn dried distillers grains with solubles (C-DDGS) on an equal NE basis would affect pig performance. Two additional experiments were conducted to determine the DE and ME of these same diets (Exp. 2) and the same C-DDGS sample (Exp. 3) used in Exp. 1 to generate data to support results obtained from the field trial. In Exp. 1, 3 barns, each containing 48 pens and 20 pigs per pen (2,880 pigs) were used. Diets were formulated to contain 0, 10, 20, and 30% C-DDGS, with calculated dietary NE and standardized ileal-digestible Lys being equal across all C-DDGS levels. The NE values (kcal/kg as is) used in feed formulation were corn, 2,557; soybean meal, 1,960; soybean oil, 7,544; and C-DDGS, 2,284. Diets were additionally formulated to meet or exceed the amino acid and mineral needs according to the NRC (2012) recommendations. There were no differences (P ≥ 0.10) noted for pig ADG, ADFI, or G:F among pigs fed the different C-DDGS levels when evaluated on d 28 (36 replications per treatment) or on d 39 (24 replications per treatment due to scale calibration error in one barn). In addition, there was no effect of dietary treatment on DP (P ≥ 0.10), suggesting that the estimates of NE used for feed formulation were relatively accurate. When the complete diets were fed to pigs in metabolism crates (Exp. 2), apparent total-tract digestibility of DM, ether extract, NDF, and phosphorus, and dietary DE and ME, increased with increasing C-DDGS levels (P ≤ 0.05). In Exp. 3, the ME in the C-DDGS used in Exp. 1 and 2 was determined to be 3,682 kcal/kg of DM, which was similar to the formulated value of 3,702 kcal of ME/kg of DM. Overall, the data suggest that the NE levels used for corn, soybean meal, soybean oil, and C-DDGS were relatively accurate given that pig performance and DP were unaffected by C-DDGS inclusion level. Differences in apparent total-tract digestibility of dietary DM, ether extract, NDF, and phosphorus could be directly related to digestibility differences in these nutrients, C-DDGS compared with corn, soybean meal, and soybean oil. These results support the formulating of diets on a NE basis, which is especially important in using alternative feedstuffs in swine feed formulation.