Study: Insect protein boosts trout immunity and lowers mortality

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Black Soldier Fly derived larvae © Maltento

A recent study has revealed that a product from Black Soldier Fly (BSF) based producer, Maltento, increases immune system responses and results in a lower mortality rate in Rainbow trout.

The South African company’s hydrolyzed insect protein/digest, Palate+ was the focus of the research. The study compared the blood proteome profiles between two groups of fish; one was fed food supplemented by Palate+, and the other was fed a standard basal diet.

The research was conducted between October and November 2023 by Cape Town’s marine surveyor company MariHealth Solutions and took place at the Sanlei trout farm in Lesotho.

Sanlei is the first African aquaculture business to obtain the prestigious Best Aquaculture Practices certification as developed by the Global Seafood Alliance, indicating the farm's commitment to established industry standards for environmentally and socially responsible seafood practices.

Lower mortality 

The Palate+ fed fish displayed lower mortality rates than anticipated.

In the study’s report, Professor Vernon Coyne, MariHealth Solutions’ CSO and co-founder, stated that “in terms of mortalities, it is important to note that C4 [the Palate+ trout cohort] performed better than what would normally be expected at certain periods during the trial compared to C5 [basic diet trout cohort].”

Stronger immune defense responses

One of the researchers involved in the study, Dr B Spolander, remarked: “It is both very encouraging and interesting that C4 showed such a notable upregulation of immune function pathways compared to C5 where so many important variables regarding immune system comparison were kept the same: genetics, location of cages, water quality variables, and the infectious agent challenge would have been very similar.”

According to Dean Smorenburg, CEO of Maltento, the stronger immune defense responses seen in trout fed Palate+ compared to those on the basal diet is likely due to the presence of chitin and the distinct proteins in the product.

Feed efficiency 

In April, the CEO told this publication that the BSF derived product funtions as a palatability enhancer and it stimulates a more aggressive feed response from fish. “Upon contact with water, the scent of insects from our PALATE+ product triggers fish to attack the pellets more vigorously, resulting in reduced food waste at the bottom of the pond. This innovative approach not only enhances sustainability but also improves the nutritional value and efficiency of feed utilization in aquaculture settings.”

Ingesting spent brewers' grain enriches fly larvae with essential nutrients, said the CEO.

The larvae at Maltento are reared on a diet comprising up to 400,000 kgs of agro-processing waste monthly, including spent grains from breweries as well as left-over rusks and baked goods from bakeries.  

“Once the larvae reach maturity, they are transformed into a nutritious 'protein smoothie.' This versatile product can be seamlessly integrated into distinct types of pet feed solutions for companion animals and the aquaculture sector, ensuring a high-quality and sustainable source of nutrition for a diverse range of animals.”

Insect biotechnology is transforming the perception of high-quality protein, Smorenburg believes. The BSF production process, said the CEO, supports a scientifically driven, regenerative, and sustainable approach that minimizes environmental impact: “The inherent nutraceutical advantages of BSF larvae, such as chitin, antimicrobial peptides, and medium-chain fatty acids, underscore the need for increased focus and investment to fully realize the potential of insects in today's context."