Manure Manager

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Using algae to clean water, feed livestock

December 2, 2013  by California State Polytechnic University

Dec. 2, 2013 – Can scientists grow algae in polluted water on dairy farms and then safely feed it to livestock?

That’s what Shelton Murinda, an associate professor of animal and veterinary sciences, Marcia Ewers of the biological sciences department, and their research colleagues at the California State Polytechnic University are trying to discover. The Department of Agriculture has awarded the team nearly $500,000 to find out.

The research has significant implications: every year, California’s dairies produce about 30 million tons of solid and liquid waste that release ammonia into the air and pollute water sources causing algal blooms that kill fish. Manure also contains pathogens that can harm other animals and humans.

“Algae is a good crop that can clean up the cow manure, because the manure is full of nutrients. We are initially targeting removal of nitrogen and phosphorus,” says Murinda, who is also director for the Center for Antimicrobial Research & Food Safety. “Algae is also a potential food source for livestock, and it’s not going to be competing for land with soybeans or corn.”


The critical question that the team is trying to determine is whether the algae would be safe enough for livestock to consume.

“Cow manure is laden with organisms that can cause disease in cows and humans, like e coli, salmonella, and listeria, including a plethora of viruses and parasites,” he says. “What is the fate of these pathogens? We don’t know yet. We’re looking at that question.”

The team also includes Tryg Lundquist and Gregory Schwartz, who are engineering professors from Cal Poly San Luis Obispo and Mark Ibewke of the USDA Research Office in Riverside.

Murinda and his team have sent algae cultures to the San Luis Obispo campus, which operates a dairy. Researchers plan to grow the algae in paddle-wheeled ponds and feed it with manure from the dairy when the project starts early next year.

Molecular biological tools will allow the researchers to study the microbial populations in the algal ponds and feedstock. If the algae carry the pathogens, one possibility is to pasteurize or dry and heat it before it is fed to livestock, he says.

If the project proves that the algae can be safely fed to livestock, the benefits would be significant, Murinda says. Farmers could grow seven to 10 times more algae than soybeans or corn in a similar area.

“It would provide a more economical food source for livestock,” Murinda says. “It could enhance the quality of agricultural products like milk and poultry, while at the same time assisting farmers to meet manure management problems.”

The project will include modeling studies that will allow researchers to better estimate the potential financial benefits to the agricultural industry.


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