The expanding aquaculture industry is currently the major user of fish meal globally. Traditional sources of fishmeal cannot continue to sustainably meet the high demand and rapid growth rates of the aquaculture industry, whilst vegetable sources come with their own challenges, both environmental and nutritional. This has led to the continuing search for sustainable fish meal replacements. Insects, thanks to their ability to convert low-value biomass into high quality animal proteins and reintroduce them in the food chain, are emerging as an excellent natural and sustainable solution to address this challenge. ProtiNovaTM is one such commercially available insect meal product, produced by Innovafeed from black soldier fly (Hermetia illucens) larvae, grown on sustainable co-products of the agricultural industry.
A 12 week growth trial with 35g rainbow trout, Onchorhynchus mykiss, was carried out in fifteen 650L tanks in the RAS facilities of AquaBioTech Innovia (Malta). Five isonitrogenous and isocaloric diets containing 15, 11, 9, 7 and 5% fish meal and 0, 4, 6, 8 and 10% ProtiNovaTM respectively, were tested in triplicate. Feeding was carried out to satiation and the average temperature during the trial was 16.7oC. After the growth trial, fish from treatments containing either 0 or 10% ProtiNovaTM were challenged with Aeromonas salmonicida and Flavobacterium psychrophilum.
The feeding trial found that including up to 10% ProtiNovaTM i.e. replacing up to 67% of fish meal, did not significantly (p < 0.05) affect FCR, SGR, TGC or SFR (Figure 1). Survival was at least 98% in all treatments. At the end of the trial period, there was no significant effects of ProtiNovaTM inclusion level on the fish condition factor (K), hepatosomatic index (HSI) or viscerosomatic index (VSI). There were no significant differences in mortality following challenge with the two pathogens (Figure 2).
This work demonstrated that ProtiNovaTM can perform as well as a high quality fishmeal in commercial trout diets.