Chilean salmon farmer will test feed additive aimed at halving SRS mortality

Researchers at the Pontifical Catholic University of Valparaíso (PUCV) in Chile have developed a bioactive feed additive designed to boost the innate immune response of Atlantic salmon against salmonid rickettsial septicaemia (SRS), reports Fish Farming Expert's Chilean sister site, Salmonexpert.cl.

The disease, caused by the intracellular bacterium Piscirickettsia salmonis, results in losses exceeding US $700 million per year in Chile and triggers intensive use of antibiotics.

PUVC said that faced with the declining effectiveness of traditional antibiotics and vaccines, feed additive Aqua P-Enhance has emerged as a technological and biosafety solution. 

Strengthens natural defences

The synthetic peptide-based additive is said to work by strengthening the fish's natural defences - as evaluated in fish immune system organs such as the anterior kidney and spleen - without directly interacting with P. salmonis. This eliminates the risk of bacterial resistance and reduces operational stress by being integrated directly into commercial diets at parts per million (ppm) doses.

“The great innovation of this development lies in the fact that it does not interact directly with the bacteria, virtually eliminating the risk of generating bacterial resistance. Instead, the compound specifically reinforces the fish's innate immune response to episodes without triggering sterile inflammation when the animal is healthy, also offering a dual function by promoting salmon growth and improving its overall hematological parameters,” said Yannick Pombett, a food engineer and PhD in biotechnology from PUCV, who leads the project.

According to Professor Luis Mercado, director of the immunology laboratory at PUCV and alternate director of the project, the initiative represents the consolidation of a line of research developed for more than two decades in the laboratory.

The proposal for the development of Aqua P-Enhance originated from the doctoral thesis of Pombett, who previously completed an international internship at the Norwegian University of Life Sciences (NMBU), in the animal nutrition research group of Dr Margareth Øverland, where he specialised in aquaculture immunonutrition.

Feed trials with Invermar

To scale the technology from technology readiness level 5 (validation in a relevant real-world environment) to  TLR 7 (prototype demonstrated in an operational environment), the project finalised a collaboration agreement with salmon farming company Invermar. It will integrate the additive into its feed production lines to carry out validations at fish farms under real world conditions, in the grow-out phase of the fish in seawater.

From an academic perspective, the researchers highlighted the value of industry taking risks in the early stages of R&D and investing in innovation.

“The product we are developing will be applied directly in the field in fish farms. This represents a significant milestone, since aquaculture companies are often reluctant to take risks during the saltwater grow-out phase,” Mercado pointed out.

Pombett added: “Invermar seeks to differentiate itself and compete by developing its own research and innovation department.”

Aiming to halve mortality

Among the projected performance goals for the technology are a 50% reduction in mortality caused by SRS, an equivalent decrease of 50% in the use of antimicrobials, and an increase of at least 10% in the final body weight of the salmon.

In addition to scaling up the technology, the researchers have established the spin-off company Peptide Aqua Solutions. It is anticipated that, after two years, once validations at Invermar’s fish farms are completed, the development team will be ready to begin marketing Aqua P-Enhance in partnership with feed manufacturers or seek funding to launch its own production plant.