Microalgae are a large of diverse group of microorganisms produci ng a variety of valuable compounds : They are the richest source of polyunsaturated fatty acids in the environment and can harbour a wide array of other compounds with beneficial health properties, including antioxidant; anti-inflammatory, antimicrobial, or anti-virulence/quorum quenching. Despite these advantages, little is known about the application of microalgae as feed adjuvant in the diet of farmed fish.
Material and methods
To investigate the potential benefits of dietary microalgae, young rainbow trout (Oncorhynchus mykiss ), of approximately 30 g; 15 cm length were allocated in between 6 feeding groups (fishmeal diet; diet enriched in soy protein; diet enriched with Chlorella sorokiniana; diet enriched with Tetradesmus obliquus; diet enriched with intact Haematococcus pluvialis ; and diet enriched with leftover H. pluvialis following extraction of the astaxanthin). Each diet was represented in triplicates 3x15 fish per treatment. The fish were maintained that way for ten weeks. Afterwards, sera were harvested for metabolite analysis and the composition of the intestinal microbiota was analysed by amplicon sequencing using primers for the V1-V3 region of the 16S rRNA.
Results and discussion
No significant effect was found on the growth of the fish. However, the diets were associated in changes in the concentration of serum’s metabolite and in the composition of the fish’ intestinal microbiota. These results suggest that incorporation of microalgae can have potential health benefits as dietary supplement in the diet of farmed fish.