April 30, 2008
Ethanol by-product might feed livestock
CARBONDALE, Ill. -- If corn can fuel cars, could the byproduct feed cows?
The answer could mean the difference between a boom and a fizzle for the burgeoning biodiesel industry, which, if it is to compete with more traditional fuels, must somehow find a use for the crude glycerol it generates as part of the manufacturing process.
Amer AbuGhazalah, an animal scientist at Southern Illinois University Carbondale, believes adding glycerol to animal feed could solve problems for both the industry and for livestock owners facing sharply rising costs for corn.
"Crude glycerol (the main byproduct created when turning biomass into fuel) and corn are both carbohydrates and have an almost equal energy value - glycerol is actually a little greater," AbuGhazalah said.
"Twenty-five to 35 percent of what cows eat every day is corn, and with the price of corn almost doubling in the last four years, mainly because of the demand for ethanol, this has had a serious effect on many farmers."
Glycerol couldn't take the place of corn, but based on his research with dairy cows, AbuGhazalh feels pretty sure it could fill in for as much as 15 percent with no adverse effects on appetite, digestion, milk production or milk composition. That would make a huge difference to producers of both biodiesel and milk.
"If crude glycerol substitutes for just 15 percent of the corn in dairy cows' daily diet, the potential market for crude glycerol in Illinois alone would be close to 60 to 75 million pounds annually," he noted.
"The price of crude glycerol is about one-third the price of corn. At 15 percent replacement, dairy producers would save at least $100 per head on feed each year."
AbuGhazalah also studied the effects of replacing 30 percent and 45 percent of the corn with crude glycerol. Here, the outcome fell under the old good news/bad news category.
At the higher rates, the glycerol-corn mixtures proved less digestible - feeling more full, the cows ate less and therefore produced less milk. But AbuGhazalh saw positive changes resulting from changes in the amounts of volatile fatty acids produced in the rumen as microbes there did their work. Increased propionate generally boosts milk production, while higher levels of butyrate improve rumen tissue health. Lower acetate levels cut methane production, leading to a more environmentally friendly cow.
AbuGhazalah believes adding fiber-dissolving enzymes to the glycerol-corn mix could solve the digestibility problem while keeping the fatty acid benefits, a theory he and SIUC dairy foreman Chet E. Stuemke are now testing at the College of Agricultural Science's new dairy research barn.
"To our knowledge, it's the first study to evaluate the use of these enzymes in diets containing crude glycerol," AbuGhazalah said.
In addition, SIUC agricultural economist Phillip R. Eberle is working with the pair to determine how much dairy farmers could save by substituting crude glycerol for corn. The team expects to report results of the project, funded by the Illinois Council on Food and Agricultural Research, by 2009.
Before he'd feel comfortable recommending that substitution, though, AbuGhazalah would prefer to follow the cows on the mixed rations through an entire lactation season to make sure they have no ill effects on health or fertility.
"We're only feeding them this diet three to four weeks," he pointed out. "We need to see what happens in the longer term."
Assuming good results there, AbuGhazalah could see a ripple effect for glycerol-corn rations.
"It could be extended to other livestock animals - beef cows, hogs, chicken, sheep and goats," he said.