Replacing fish meal and fish oil in aquaculture

Some aquaculture species, such as salmonids and crustaceans, are major consumers of fish meal and fish oil. Such feeds come from industrial fisheries and fish processing.

What could be done to compensate if fish meal and fish oil are ever lacking?
Increasing the share of plant-based ingredients in fish feed works as a privileged alternative. However, plants do not have the same nutritional properties as fish byproducts, so what are the guidelines to follow for finding substitutes?

Several factors must be considered in the event that the share of plants in fish feed is increased. What are these factors?

Elements such as phytoestrogens (found in lupine, soybean, or alfalfa for example) can thus disturb the hormonal cycle of certain breeding species. Another example of this kind of element is gossypol. Found in cottonseed cake, it can decrease the performance as well as the level of ingestion of some species. Another risk worth mentioning associated with these factors is the mycotoxin content of plant raw materials.

Fish meal contains a significant amount of minerals that are well digested by various aquatic species. The possibility of readjusting phosphorus, calcium, and other minerals levels should therefore be considered as a potential alternative for instance at the formulation stage.

In addition to being highly sought after by consumers, long-chain polyunsaturated fatty acids are essential nutrients for the growth of aquatic animals. For this reason, the fatty acid profile of farmed fish and shrimp is heavily influenced by the lipid composition of their ingested feed. Some species, including freshwater ones, have the ability to synthesise polyunsaturated fatty acids. Yet marine fish, such as seabass or seabream, are completely devoid of this ability. Therefore, these essential fatty acids must be provided to them through their feed.
However, raw materials that can provide such nutrients without being derived from fish processing scarcely exist. Microalgae, insect meal, and GM plants are among some possible substitutes. While the two first options have only barely been explored, the use of GMOs has proven relatively successful from a zootechnical point of view. However, this option still has a long way to go before it can gain widespread acceptance, especially within the European Union.

Whatever your feed issue, experts from Techna are at your service, thanks to our thorough knowledge, experience, and accuracy in meeting farm animals’ nutritional needs. We assist feed manufacturers in finding alternatives to fish by-products for the benefit of plants. For more information, please don’t hesitate to contact our experts at the Techna Group.