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A byproduct of biodiesel may be used to support the production of an animal feed additive to enhance the performance and growth of dairy cattle.

Ohio State University (OSU) department of animal science researchers have received a $38,733 one-year grant from the Ohio Soybean Council to use crude glycerol to grow yeast – a common feed supplement in dairy cattle diets. The researchers are evaluating whether or not glycerol can effectively be used to grow yeast and how that yeast stacks up to commercial varieties in quality and in price.

"The idea behind the project is to take what is considered a waste product and turn it into a value-added agricultural commodity," says Zhongtang Yu, a microbiologist with the Ohio Agricultural Research and Development Center and principal investigator of the project.

Approximately 1.1 million tons of crude glycerol is produced annually from production of biodiesel, mainly soy-based. The crude glycerol has little market value because of its impurities. In some cases, the glycerol is refined and used in a variety of skin care and cosmetic products. However, with biodiesel production increasing, finding a market for glycerol is becoming increasingly difficult. Yu speculates that the byproduct could be used as a food substitute for yeast microbes.

"Crude glycerol is unrefined, yet microbes like yeast don't care about the impurities," says Yu. "We wanted to see if we could use the glycerol as feed to grow yeast and then use that yeast in dairy cattle diets."

The challenge for Yu is to find yeast that can be grown using glycerol.

"There is no known published literature citing that yeasts can be grown using glycerol, so we are going to have to try different yeast species strains to see what works and what doesn't," says Yu.

If that portion of the project is successful, OSU Extension dairy specialist Maurice Eastridge plans to compare yeast produced from crude glycerol to commercial yeast products that are used in dairy cattle feed.

"We'll be looking at things like digestibility and whether the glycerol-produced yeast is equal to or better than the commercial products in improving animal performance," says Eastridge. "We also want to see if we can produce the product more cheaply."

In addition to this project, researchers are studying the various components of crude glycerol – such as methanol, fatty acids, and minerals – to determine any toxic effects on yeast microbes.