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

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 CDDGS 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 totaltract 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.