As more pork producers build interest in feeding distillers dried grains with solubles to growing pigs, many questions remain about the product’s digestibility.

“Previous research shows that while the amount of energy in DDGS is greater than that of corn, pigs have lower digestibility of energy in DDGS than in corn,” notes Hans Stein, University of Illinois swine nutritionist. “Our goal was to find out why.”

Stein’s team wanted to better understand the digestibility differences between DDGS and corn. Fiber content is the iiggest difference between the two, and fiber contributes to DDGS’ total energy, but not much is known about how pigs utilize the fiber in DDGS.

“We want to find ways to improve the utilization of this energy source in a swine diet,” he says.“But first we need to understand fiber’s  role in DDGS.”

The group’s research demonstrated that overall, utilization of fiber in DDGS is low-- less than 50 percent. Fiber is characterized as soluble or insoluble fiber.

The soluble fiber consists of pectins, some hemicelluloses and some oligosaccharides. Soluble fiber will change the viscosity of the digesta in the animal’s intestinal tract while absorbing water and becoming easily fermentable there,” Stein adds.

On the other hand, insoluble fiber will not dissolve in solution and is made up of the plant’s hardest parts such as cellulose and lignin. These fibers do not change viscosity in the intestinal tract and they are the most difficult to ferment.

“Pigs utilize soluble fiber very well, almost 90 percent,” Stein says. “Unfortunately, most of the fiber in DDGS is insoluble and has much lower digestibility. It’s the reason for the low digestibility of the combined fiber fraction in DDGS. However, if we can do anything to change the fiber and make it more soluble, we know we can increase the utilization.”

From a practical standpoint, DDGS’s higher insoluble fiber content means more undigested material goes straight into the manure, which in turn creates more manure management issues for producers.

“A higher fiber content in the manure creates a thicker slurry, which could lead to more solids in the pit,” says Matthew Robert, University of Illinois visiting research engineer in agricultural and biological engineering. “This requires agitating the slurry in the pit for a longer period to get the solids moving for pump out. If more solids remain in the pit after it’s pumped, it results in less future storage.”

In addition, the research opened doors to new research methods.

“We know that fiber could be measured in many ways,” Stein notes “A standard measurement method, Total Dietary Fiber, is very expensive. We found a less expensive procedure, Neutral Detergent Fiber, to be quite effective and closely correlated to TDF.”

Stein’s team is continuing to look for ways to increase fiber’s solubility and in turn, find new ways for animals to require less feed to produce one pound of gain.

This research titled, “Digestibility of dietary fiber in distillers coproducts fed to growing pigs,” was published in the Journal of Animal Science by Pedro Urriola and Hans Stein of the University of Illinois, and Jerry Shurson of the University of Minnesota. Funding was provided by the National Pork Board and the Minnesota Pork Producers Association.

Source: University of Illinois