The rapidly increasing production of ethanol is generating large amounts of distillers’ co-products that are available for swine feeding programs. These co-products can help reduce feed cost. There are several challenges, however, when including such co-products in swine diets. An example of these co-products is distillers dried grains with solubles (DDGS). The greater concentration of dietary fiber in DDGS than in corn and soybean meal has been constantly mentioned among the factors that cause those challenges. The efficiency by which the pig will utilize the energy in DDGS is directly affected by the digestibility of dietary fiber. To measure the digestibility of dietary fiber in DDGS is, therefore, the first step towards optimization of the utilization of energy from DDGS.
Dietary fiber is the sum of carbohydrates that are resistant to digestion and absorption in the small intestine and that are susceptible to partial or complete degradation (fermentation) in the large intestine (AACC, 2000). There are, however, no data on the digestibility of dietary fiber in DDGS by growing pigs. Therefore, the objective of these experiments was to measure the digestibility of dietary fiber in DDGS by growing pigs and to measure the difference in fermentation capacity among different sources of DDGS. The apparent ileal (AID) and apparent total tract digestibility (ATTD) was measured and the fermentation of dietary fiber in DDGS was calculated by subtracting values for AID from values for ATTD. Ileal and fecal samples from 3 experiments were analyzed. Results show that the AID, ATTD, and fermentation of total dietary fiber (TDF) among corn DDGS sources are different. The AID of TDF ranged between 12.6 and 38.2%, the ATTD of TDF ranged between 23.4 and 57.0%, and the fermentation of TDF ranged from 10.5 to 38.6%. Those differences in digestibility and fermentation properties of the different sources of DDGS can explain the variation in digestibility of energy that has been previously reported. This suggests that the digestibility of dietary fiber in DDGS needs to be improved to increase the digestibility of energy.
The soluble dietary fiber (SDF) is degraded and absorbed faster than the insoluble dietary fiber (IDF). The AID of SDF was 64.4% while the AID of IDF was only 20%. This indicates that sources of DDGS with greater concentration of SDF have a greater feeding value than sources with greater concentration of IDF. Also, processes that increase the concentration of SDF help in improving the utilization of dietary fiber by pigs.
Results also showed that there is no difference in AID or ATTD of TDF between DDGS produced from corn and DDGS produced from sorghum. These data also suggest that DDGS from the fuel ethanol and the DDGS from beverage production are similar in terms of digestibility of dietary fiber. However, the AID of TDF is greater in DDGS than in distillers dried grains (DDG), but there is no difference in the ATTD of TDF between DDGS and DDG.
In conclusion, data from these experiments suggest that the digestibility and fermentation of the dietary fiber in DDGS is less than 50%. This low digestibility of fiber in DDGS is the reason why energy and DM digestibility is lower in DDGS than in corn. It is necessary, therefore, to identify factors that may increase the fermentation of dietary fiber in DDGS to increase the digestibility of energy from DDGS.
Contact information:
Principal Investigator and Title: Hans H. Stein, Associate Professor
Institution: University of Illinois, 1207 W. Gregory Dr., Urbana, IL 61801
Email: [email protected]