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Biofuel byproducts could have new life as poultry feed

text and photos by Fred Miller

As diversion of corn and soybean crops to ethanol and biodiesel production reduces supply and increases costs for poultry feed, University of Arkansas Division of Agriculture scientists are studying how to turn biofuel byproducts into feed supplements that can help manage costs while providing efficient nutrition for the birds.

Dr. Park Waldroup, the Novus International Distinguished Professor of Poultry Science, has shown that the dried corn residue that remains after ethanol production is a suitable substitute for some of the corn and soybean meal in poultry feeds.

"We first looked into it in the '80s when there was a surge of on-farm ethanol production," Waldroup says. "We began to look into it again when it became clear that a lot more corn was going to go toward ethanol."

Waldroup, a poultry nutritionist, studies the use of distiller's dried grains with solubles, or DDGS, as a substitute for some of the grain content in poultry feed. "We've found that DDGS can replace both corn and soybeans," he says.

FORMING FEED - Poultry scientist Park Waldroup and graduate student Cesar Coto operate a machine that forms poultry feed ingredients into pellets.

Waldroup says it's important to pay attention to protein balance when using distillers' grains. The distilling process that removes ethanol from the grain concentrates fiber, protein and oil about threefold, he says. DDGS contributes a lot of corn protein and can replace a lot of soybean protein, but its usefulness in poultry digestive systems can be problematic.

"You have to deal with the limitations of DDGS," Waldroup says. "It's not as digestible as corn or soybean meal."

The physical structure of the feed is also important because of the way the poultry digestive system works, Waldroup says. DDGS is bulkier than corn or soybean meal, containing a third more weight per volume. This higher bulk makes the chickens feel fuller with less volume, so they eat less and don't grow as much.

Waldroup has been experimenting with the milling process to develop distiller grains into a more compact and durable pellet that is more suitable for poultry digestion.

Waldroup anticipates an eventual change in the availability of DDGS. For poultry feed, he says, the most valuable ingredient in the distiller grains is the oil, which supplies ample energy for growth. But alternative fuel industries are now looking at the feasibility of using the oil from distiller grain, after it has been used to make ethanol, to make biodiesel.

Waldroup has shown that glycerin, which is extracted from soy and other oils during biodiesel production, is very useful for poultry diets.

"Glycerin is a pure carbohydrate," Waldroup says. "It's a pure energy source and chickens use it quite well." When added to poultry feed, glycerin can contribute to chicken growth, Waldroup says. He is conducting the same research now with glycerin extracted from canola oil. Canola is an attractive biodiesel source because it can produce three times as much oil per acre as soybeans.

CAN-DO CANOLA - Yuna Min, a visiting poultry scientist from China, conducts a feeding trial for canola residue remaining after ethanol production.

Waldroup conducts feeding trials to track how well the chickens grow on the experimental feeds. "We also test the quality of the final product," he says.

"We've discovered that glycerin tends to improve breast meat yield and DDGS tends to decrease yield," Waldroup says. "We don't know why."

"It may be that glycerin can be added to feed made from DDGS to counter the yield loss," he says.