Most livestock nutritionists recognize dried distillers grains with solubles (DDGS) as a source of fat and protein. As a result, researchers have devoted a significant amount of time and resources to better characterize the fat and amino acid components of DDGS.
However, we often overlook that a significant amount of DDGS is comprised of fiber. In fact, fat content (8 percent dry matter [DM]) is much less than the fiber component, while typical crude protein concentrations (31 percent DM) are similar to the concentration of the ash-free neutral detergent fiber (aNDFom) fraction (31 percent DM; Table 1).
A challenge with any fiber discussion is accurately defining the fiber terms being compared. Components such as acid detergent fiber (ADF), neutral detergent fiber (NDF), crude fiber, total dietary fiber and soluble dietary fiber arecommonly used, and each term reflects a different part of the fiber component. The fiber measures used most often in the dairy industry to describe DDGS include ADF and NDF. Generally speaking, the ADF fraction includes cellulose and the lignin component while NDF includes ADF plus the hemicellulose fraction.
We can also consider the digestibility of these fractions to evaluate fiber quality in DDGS. Methods to determine digestibility estimates have traditionally been obtained through in vivo or in situ studies. These were time consuming, expensive and highly variable – and, as a result, very few nutritionists saw value in trying to determine fiber digestibility of DDGS. However, in vitro systems have evolved to better predict response in the animal and, as a result, nutritionists now have the option of submitting DDGS samples to determine digestibility.
Continue reading this article published in Progressive Dairyman.
