The Iowa State University Department of Animal Science recently concluded tests conducted throughout 2007 that assessed the viability of crude glycerin as an animal feed. The results indicated that the byproduct of biodiesel production is viable and comparable to corn, as reported in Biodiesel Magazine.
Although the crude glycerin was determined to be a viable
energy-creating feed, Kerr said the ever-fluctuating markets ultimately
determine its use. “Corn would be cheaper,” he said, referring to the present
situation. “When we started [testing], glycerin was 3 cents a pound. Corn at
that time was maybe 6 cents a pound.” However, now glycerin is 20 cents per
pound. “At 20 cents a pound, it’s too expensive as an energy source,” he said.
The testing consisted of energy-balance experiments that determined the
effect of carefully applied dietary treatments, which ultimately rendered a
metabolized energy number. “[We] feed them a known quantity of feed or test
ingredient, and then determine how much energy they have consumed from that diet
and how much energy has been excreted in the feces or urine to come up with a
metabolized energy number,” Kerr explained.
Crude glycerin is 85%
glycerin, 10% water and 5% salts, as opposed to refined glycerin, which is more
than 99% glycerin with no impurities. Refined glycerin can be used to make
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Iowa State University
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