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Maggots to help feed fish and reduce cow manure

Published on 15 September, 2007, Last updated at 14:22 GMT
Maggots for rainbow trout feed

Cow manure and fish guts and maggots. It could all soon be dinner - if you are a rainbow trout.

University scientists here are working on a new maggot-based feed capable of fattening rainbows for the dinner table, while simultaneously helping slash growing mounds of manure and fish entrails.

Aquatic species veterinarian Sophie St. Hilaire suggested there was a way the two industries could help one another — with dairies using a slurry of cow dung and trout intestines to grow maggots rich in fatty acids that make fish better for humans.


First, manure is gathered in buckets, then seeded with fly eggs imported from a commercial insect grower. About 70 days later, fish guts are added to help enrich the maggots with heart-healthy omega-3 and omega-6 fatty acids. The resulting maggots eventually wriggle up specially built ramps — only to drop through holes into waiting buckets.

The maggots are then washed, frozen and ground up to be fed to rainbow trout at the test station along the Snake River.

The next step is to raise fish to harvestable size, then in taste tests to determine if they are comparable in flavour and texture to trout raised on traditional commercial fish food.


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