Distillers dried grains with solubles, or DDGS, is a co-product of the rapidly growing ethanol industry. DDGS has been increasingly used for swine diets because of its affordability and nutritive value. Corn DDGS is high in energy, amino acids, and digestible phosphorus.

In the last few years, more ethanol plants have started  to use centrifugation to extract oil from DDGS for use in the production of biodiesel. The resulting DDGS products contain less fat than conventional DDGS. Reduced-fat DDGS products would be expected to have decreased digestible (DE) and metabolizable (ME) energy concentrations compared with  conventional DDGS, but energy values for these products have not yet been reported.

An experiment was conducted to determine the concentrations of DE and ME in three sources of distillers dried grains with solubles (DDGS) containing different fat concentrations. In addition, the effect of supplementing diets containing reduced-fat DDGS products with corn oil to increase DE and ME concentrations was determined.

A total of 48 barrows with an average initial body weight of 15.4 kg were used in the experiment. A basal corn diet and five experimental DDGS diets were formulated. Three of the diets contained 48% corn and 50% of either high-fat (HF-DDGS; 9.56% fat), medium-fat (MF-DDGS; 8.11% fat), or low-fat (LF-DDGS; 6.63% fat) DDGS. Fat content was determined as acid-hydrolyzed ether extract. Two additional diets were formulated by adding 1.5% or 2.5% corn oil to the MF-DDGS diet or the LF-DDGS diet at the expense of MF-DDGS or LF-DDGS, respectively, to bring total concentrations of fat in the MF-DDGS and LF-DDGS diets close to the concentration of fat in the HF-DDGS diet.

On an as-fed basis, the concentrations of DE and ME  were greater (P < 0.01) in HF-DDGS than in MF-DDGS and LF-DDGS, which did not differ from each other (Table 1). However, on a dry matter basis, DE and ME concentrations in HF-DDGS were not significantly greater than in MF-DDGS and LF-DDGS, although they were numerically greater.

One reason the DE and ME values did not differ is that MF-DDGS and LF-DDGS contained more protein ( 27.4 and 27.1%, vs. 25.2%) and NDF (30.7 and 29.9%,  vs. 28.6% respectively) than conventional high-fat DDGS. Energy derived from these nutrients partly offsets the reduced energy that is obtained from fat. Another reason is that the digestibility of fat in DDGS is only around  60%, which results in less of an impact on DE and ME  than would otherwise have been expected.

The apparent total tract digestibility of gross energy was not different among experimental diets. The digestibility of energy in corn oil is much greater than in DDGS, but there may not have been enough corn oil in the diets to significantly affect their overall energy digestibility.

The concentrations of DE and ME in the diets containing HF-DDGS, MF-DDGS, MF-DDGS+oil, and LF-DDGS+oil were not different. DE and ME concentrations were less (P < 0.01) in the LF-DDGS diet than in the HF-DDGS diet, but did not differ from the MF-DDGS, MF-DDGS + oil, or LF-DDGS + oil diets. Adding corn oil to the diets numerically increased DE and ME in both MF-DDGS and LF-DDGS diets, and made the DE and ME concentrations in the LF-DDGS diet comparable to those in the HF-DDGS diet.

• Reduced-fat DDGS products contain less gross energy than conventional DDGS.
• The concentrations of digestible and metabolizable energy in reduced-fat DDGS products are less than in conventional DDGS, but not as much lower as might be predicted from the difference in gross energy. This is probably due to the increased concentrations of protein and NDF in reduced-fat DDGS products, and to the fact that fat digestibility in DDGS is relatively low.
• Addition of supplemental oil or fat to diets containing reduced-fat DDGS products may compensate for the reduction in energy concentration.

Table 1. Concentrations of gross (GE), digestible (DE), and metabolizable (ME) energy in high-fat (HF-DDGS), medium-fat (MF-DDGS), and low-fat (LF-DDGS) distillers dried grains with solubles

^a,b Means without a common superscript within a row are different (P < 0.05).

Table 2. Energy concentration and digestibility in diets containing HF-DDGS, MF-DDGS, and LF-DDGS and in diets supplemented with corn oil

^a,b Means without a common superscript within a row are different (P < 0.05).

This report is based on unpublished data by D.Y. Kil, J.W. Lee, and H.H. Stein.