Livestock feed production from fish by-product silage

Problem statement

The increase of fish by-products (tissues, viscera, etc.) in the processing industry generates a large environmental impact by promoting the proliferation of harmful bacteria. Poultry slurry is a problem on farms as it accumulates, affecting the quality of life of poultry and entailing significant costs in management and disposal.

Executive summary

A liquefaction process prepares the fish for ensiling. This occurs due to the presence of enzymes naturally present in the fish, and is accelerated by the acid, creating suitable conditions for the enzymes to break down the tissues, while limiting the growth of harmful bacteria.

Technology description

Fish silage can be made from all fish species and their respective parts separately. The final quality of the silage depends on the degree of freshness of the raw materials. The fish by-product silage process is based on the liquefaction of raw materials such as fish viscera and skin. It starts with grinding, followed by an acidification process, where acids, enzymes and lactic acid producing bacteria are added to break down the tissues. The mixture is then shaken to homogenise the medium. Finally, this mixture is ensiled and the silage product obtained is heated, centrifuged and two products are obtained, protein hydrolysate and silage oil. The former is used in aquaculture for the growth of species other than the species of origin and as an organic agricultural fertiliser. The resulting oil is used for biodiesel production.

Market deployment considerations


Environmental considerations


Technology feedstock

fish by-products fish waste

Type of process


Technology output

fish silage


Village, Community

Technology Readiness Level







Private sector

Technology owner/developer

Azti tecnalia
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