Searching for unknown growth factors in fishmeal

“Marine ingredients are natural products that provide a complexity of nutrition with knowns and unknowns that unexpectantly aid nutrition, but we need to know more,” it was said in a recent IFFO webinar.

August 16, 2022

In a recent webinar, part of the In Focus series that is organizing the Marine Ingredients Organisation - IFFO, Dominique Bureau, Professor of Animal Nutrition and Aquaculture at the University of Guelph and Brett Glencross, technical director, IFFO, put together their knowledge on fishmeal and feed to identify the unknowns and gaps of knowledge that are still to be explored.

Many studies are being constantly published on fishmeal replacement but as Bureau noted “it’s not about replacement but effective inclusion, about knowing what the animal requires. Fishmeal is no longer a dominant ingredient and other replacement ingredients are often more expensive and less sustainable.”

Another common point of confusion is seeing fishmeal, or any other ingredient, as a single product. There is huge variability between differently sourced fishmeals, allowing their strategic use to be identified and tailored. Glencross noted that “research papers often fail to mention the grade of fishmeal used, we need to understand the diversification of the product. Marine ingredients industry is becoming a bespoke sector selling a specialist strategic ingredient.”


Bureau said that “fishmeal has all the positive components and is a more rounded ingredient when compared with others.”

Glencross noted three primary points of interaction following an animal being fed; feed intake, digestion and utilization or growth. He noted that in his trials, he has experienced a threshold of around 15% fishmeal inclusion and less than this caused a sharp drop in intake and growth. When both fishmeal and fish oil were removed, survival rates dropped significantly. Intake and palatability, remain the first and most important hurdles and need to be monitored in both the short and long term due to their effects on metabolism and life stages.


Beyond the known components, fishmeal still has an X factor which remains unanswered. Bureau labeled “fishmeal as a good insurance policy to maintain quality fish feeds and ensure healthy fish, thanks to these unknown qualities”. Bioactives, of an insoluble protein origin in marine ingredients, may be the answer and have been reported in some studies. Other potential candidates include the effect of natural hormones in the fishmeal on the fed fish, with these impacting certain species more than others. On this Bureau responded that “we cannot rush to conclusions, we don’t have a perfect understanding of the value of the ingredients or the requirements of the animal, so we need to be cautious”.

The financial component of feed variation cannot be ignored. The best feed will not always make a farmer money, and in the end, money is made by selling the final product, but the quality is key and replacing too much fishmeal can impact this.

Glencross concluded that “marine ingredients are natural products that provide a complexity of nutrition with knowns and unknowns that unexpectantly aid nutrition, but we need to know more.”

Watch the webinar here.