By CELESTE BAUMGARTNER
Ohio Correspondent

COLUMBUS, Ohio — Glycerol, a by-product of biodiesel, could possibly be used in the production of a type of yeast that is used as an animal feed additive for dairy cattle.

Ohio State University 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.

“Yeast has been fed to animals, particularly ruminant animals, for a long time,” said Maurice Eastridge, OSU extension dairy specialist. “It’s had the benefit of improving digestibility, particularly of the fiber in the diet, so it’s a very common feed additive.”

Triglyceride, a fat, is used in making biodiesel. Only the fatty acid is used, leaving the glycerol, which is a by-product, Eastridge said. The fat is different depending on the energy source but the glycerol is all the same. Approximately 1.1 million tons of crude glycerol is produced annually from the production of biodiesel – mainly soy-based, but also reprocessed restaurant oils and greases.

The crude glycerol, a clear, thick liquid, has little market value because of its impurities. It is sometimes refined and used in skin care and cosmetic products; however, with the increase in biodiesel production, finding a market for glycerol is becoming more difficult.
The researchers will experiment with feeding the glycerol to different types of yeast microbes.

“They don’t typically grow yeast on glycerol,” Eastridge said. “But there are some strains of yeast that use glycerol. We saw the opportunity then, to use a by-product to potentially grow the yeast and then we can harvest the yeast as a feed additive for dairy cattle.”

Research is just in the beginning stages. Eastridge and Zhongtang Yu, a microbiologist with the Ohio Agricultural Research and Development Center and principal investigator of the project, are collecting different strains of yeast to see if they will grow and proliferate on glycerol. “Right now we need to isolate strains of yeast that grow, and then once we do that we’ve got to grow enough of them to feed to the cattle,” Eastridge said. “Then we’ve got the animal part of the experiment that will take a little while, too. The animal experimenting will be done on a farm setting.”
The glycerol is already being used as an energy source feed additive for cattle, but researchers see this as an opportunity to grow organisms on it that will have some benefit to improving digestibility of the animals’ diet.

“It can be produced at a reasonable cost, so the cost-to-benefit ratio is very positive for yeast,” Eastridge said. “A lot of dairy farms do have this in their diet for their cows, so there is a reasonable market share to potentially penetrate.”

Within a year or two Yu and Eastridge should have a good indication if the project will be successful.

“We’re trying to improve the overall efficiency of the system by utilizing a by-product from the energy system, and then also taking that by-product to grow organisms to improve the efficiency of the animal,” Eastridge said.