Search continues for alternatives to fishmeal, fish oil in aquaculture feed

NEW ORLEANS, Louisiana — With feed the key cost factor in raising seafood on a farm, the aquaculture industry is continuing its quest toreplace expensive fish meal and fish oil in animal diets.

Scientists are examining the potential for a diverse array of non-traditional ingredients like seaweed, mushrooms and beef tallow in labs across the globe, but the scalability remains a challenge.

There have been a number of steps in labs toward total fishmeal and fish oil replacement, noted John Davidson, a senior research associated with the Freshwater Institute, where a study showed that it is possible to get equal growth in Atlantic salmon fed a fishmeal-free diet.

But that study is just one step toward total replacement of fishmeal and fish oil on an industrial level, a goal he thinks is eventually possible on a market scale, he told Undercurrent News on the sidelines of the World Aquaculture Society’s Aquaculture America conference last month.

Alternative feed sources are “always required in aquaculture for sustainability, increased feeding efficient, cost effectiveness and increased profits,” Francisca George of Nigeria’s University of Agriculture told an audience at the conference.

She has been studying the use of oyster mushrooms as an alternative feed source for Nile tilapia.

Researchers are also evaluating dried seaweed as a partial protein replacement for fish meal in shrimp diets; wheat gluten on gut health and growth performance of rainbow trout, and cottonseed flour and oil as replacements for menhaden fish meal protein in juvenile black sea bass.

And there are numerous research efforts looking into soy-based alternative feeds.

Lower soybean meal costs are a positive for the tilapia industry, where feed makes up more than half of the costs of growing the fish, Rabobank senior analyst Gorjan Nikolik told Undercurrent on the sidelines of the conference.

However, soy shortages are going to be prevalent over the next decade, driving soybean prices higher, and algae will be an important protein source in the future, David Hazlebeck, CEO of Global Algae Innovations, told an audience at the conference.

But algae production costs are currently 10 times too high for a number of reasons, even though costs are coming down as there has been a lot of investment in algae as a biofuel source, he said.

Algae yields more protein per amount of land used for production than soybeans or canola, he said.

With aquaculture using more plant-based ingredients in feed, externalities of that such as pollution form nutrient runoff associated with soybean production need to be considered, noted David Love, an assistant scientist at Johns Hopkins Bloomberg School of Public Health.

It isn’t just plant-based sources that are being examined as alternatives to fishmeal and fish oil.

Feather meal is also a potential aquaculture feed source alternative, Love told an audience at the conference.

But he also voiced concerns that antibiotics used at poultry farms in the US and China have shown up in feather meal.

Beef tallow appears suitable for use in hybrid striped bass feeds, said Jesse Trushenski, assistant professor at Southern Illinois University’s department of zoology.

The rendered beef fat product may effectively reduce the requirements for a certain type of fatty acid in fish, said Trushenski, who has also looked at canola, corn, flaxseed, coconut and palm oils.

Trushenski’s study, which examined beef tallow as an alternative to fish oil, saw elevated feed conversion ratios when fish were fed food including beef tallow and DHA, she told an audience at the conference.

Studies have also been done on beef tallow for Atlantic salmon and pompano, she said.

 

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