Functional proteins for low fishmeal diets


Aquafeed production has passed 40 million tonnes globally, demanding an increased amount of high-quality protein. Stagnated fishmeal supplies, combined with increasing raw material prices, have stimulated the adoption of alternative plant-based and rendered ingredients. Novel protein sources such as insect meal, single cell proteins, yeast and algae are also increasing.


The most frequent negative outcomes when replacing fishmeal are decreased feed attraction and palatability, which can lead to lower feed consumption, resulting in reduced essential amino acids and energy digestibility. This can result in inferior fish performance, impaired feed efficiency, and the reduction of essential micronutrients and fatty acids.


Furthermore, alternative ingredients can carry anti-nutritional factors such as saponins, tannins, lectins, etc. These compounds are not completely inactivated or destroyed during feed processing, potentially causing acute or chronic metabolic disorders. Soybean-induced enteritis in Atlantic salmon is a well-known example of how a feed ingredient can disrupt gut health by initiating an inflammatory process.

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Supporting fishmeal replacement strategies with Prosaf®

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Functional protein sources, such as Prosaf®, can play an important part in supporting fishmeal replacement strategies, by improving feed palatability, increasing digestibility with highly bioavailable essential amino acids, and potentially supporting the improvement of gut health status. Prosaf® is a high protein purified yeast extract obtained from primary culture of a proprietary Saccharomyces cerevisiae yeast strain. Prosaf® is more than 63% protein, most of which consists of essential amino acids, glutamic acid, nucleic acids and low molecular weight peptides

functional proteins aquaculture
functional proteins aquaculture

Delivering high digestibility and bioavailability

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Prosaf® has 46% of its amino acids in free form, delivering proven high digestibility and bioavailability in shrimp.


Prosaf® essential amino acid apparent digestibility for the shrimp L. vannamei (In vivo trial: Sparos Lda – Portugal) – figure 1.


Total protein digestibility of Prosaf® supplemented feeds in shrimp (In vivo trial: Prince of Songkla University – Thailand) – figure 2.

Increased digestibility with Prosaf®

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Due to its purity, Prosaf® has superior digestibility in rainbow trout compared to regular yeast extracts, and can be a more concentrated source of essential nutrients.


Total and digestible levels of crude protein (figure 1), and amino acids (figure 2) of Prosaf® compared to a regular yeast extract in rainbow trout Onchorhynchus mykiss (In vivo trial: Sparos Lda – Portugal).

functional proteins aquaculture
functional proteins aquaculture

Stimulating feed consumption with Prosaf®

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The high level of free amino acids, specifically glutamic acid, alanine, arginine and glycine, gives the product great ability to stimulate feed consumption, compared to low fishmeal diets in shrimp.


Prosaf® effect on the shrimp L. vannamei consumption preference in reduced fishmeal diets. A – high fishmeal diet (12%) compared to low fishmeal diet (3%) (figure 1).
Low fishmeal diet (3%) compared to low fishmeal diet supplemented with 2% of squid meal (figure 3).
Low fishmeal diet (3%) compared to low fishmeal diet supplemented with 2% of Prosaf® (In vivo trial; Labomar – Brazil) (figure 3).

Improving feed conversion rates with Prosaf®

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Highly digestible amino acids combined with a consistent feeding response results in improved feed conversion.


® supplementation effect on feed conversion in shrimp fed, with reduced fishmeal diets (In vivo trial: Prince of Songkla University – Thailand) (figure 1)
Prosaf® supplementation effect on feed conversion rate in largemouth bass (In vivo trial: Yangtze University – China) (figure 2)

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