Fungi biomass. Credit: University of Borås

A research project within Resource Recovery at the University of Borås in Sweden explored how valuable substances can be extracted from organic waste—such as animal manure—and how this loop can be closed by producing animal feed.

In her doctoral project, Clarisse Uwineza demonstrated how food waste and animal manure can be converted into valuable volatile fatty acids. These acids can then be used as a substrate to cultivate protein-rich fungal biomass, which in turn can be used to produce animal feed.

Organic waste, such as food waste and manure from agriculture, is a growing environmental issue. However, by using a method known as anaerobic digestion, where microorganisms break down waste in an oxygen-free environment, it is possible to extract these volatile fatty acids. These acids, along with nutrients such as nitrogen and minerals, can then be used to cultivate a specific fungus: Aspergillus oryzae. The fungus grows into a biomass rich in protein, minerals, and dietary fiber, and is also easily digestible for animals.

“My work shows that organic residues can serve as a valuable raw material for sustainable protein production, helping to close the loop in a circular economy and potentially reducing the use of protein sources such as soy and fishmeal, which currently form the basis of animal feed production,” said Uwineza.

“One thing that surprised me was how effectively the fungal biomass grew on waste-derived acids, even though some of these acids are toxic at high concentrations,” she said.

By developing a controlled method for adding the volatile fatty acids, she was able to ensure the fungus grew gradually and safely, resulting in higher yields and improved quality.

In addition to animal feed, the fungal biomass can also be used in the production of bio-based materials, such as biodegradable plastics or as an alternative to leather. The results show that emissions can be reduced, resources can be better utilized, and new opportunities can be created within the circular bioeconomy.

The project directly supports several of the UN’s Sustainable Development Goals, including Goal 12 on responsible consumption and production, Goal 13 on climate action, and Goal 2 on ending hunger.

Provided by University of Borås

Citation: How manure can be transformed into animal feed (2025, November 6) retrieved 6 November 2025 from https://phys.org/news/2025-11-manure-animal.html

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