Processed Animal Proteins from Insect and Poultry By-Products in a Fish Meal-Free Diet for Rainbow Trout: Impact on Intestinal Microbiota and Inflammatory Markers

Abstract

Sustainability of aquaculture is tied to the origin of feed ingredients. In search of sustainable fish meal-free formulations for rainbow trout, we evaluated the effect of Hermetia illucens meal (H) and poultry by-product meal (P), singly (10, 30, and 60% of either H or P) or in combination (10% H + 50% P, H10P50), as partial replacement of vegetable protein (VM) on gut microbiota (GM), inflammatory, and immune biomarkers. Fish fed the mixture H10P50 had the best growth performance. H, P, and especially the combination H10P50 partially restored α-diversity that was negatively affected by VM. Diets did not differ in the Firmicutes:Proteobacteria ratio, although the relative abundance of Gammaproteobacteria was reduced in H and was higher in P and in the fishmeal control. H had higher relative abundance of chitin-degrading Actinomyces and Bacillus, Dorea, and Enterococcus. Actinomyces was also higher in H feed, suggesting feed-chain microbiome transmission. P increased the relative abundance of protein degraders Paeniclostridium and Bacteroidales. IL-1β, IL-10, TGF-β, COX-2, and TCR-β gene expression in the midgut and head kidney and plasma lipopolysaccharide (LPS) revealed that the diets did not compromise the gut barrier function or induce inflammation. H, P, and H10P50 therefore appear valid protein sources in fishmeal-free aquafeeds.

Modulation of Atlantic salmon (Salmo salar) gut microbiota composition and predicted metabolic capacity by feeding diets with processed black soldier fly (Hermetia illucens) larvae meals and fractions

“…Such taxa have also been identified in BSF whole larvae/prepupae or their gut [ 67 – 70 ]. The microbiota in all diets contained Photobacterium , but made up more than 50% of the microbiota in the control feed, similar to previous reports [ 60 ]. Photobacterium is widely distributed in marine environment and fish [ 71 , 72 ].…”

“…The present study showed that inclusion of meals and fractions of insects in the diet can modify the gut microbiota of Atlantic salmon pre-smolts. Previous findings also showed that feeding BSF modulated gut microbiota in rainbow trout [ 27 – 29 , 41 , 60 ] and salmon post-smolts [ 26 ]. The phyla Firmicutes , Proteobacteria , Actinobacteriota , and Bacteroidota represented more than 94% of the gut microbiota in fish, regardless of the diet, which belong to the core gut microbiota in different fish species [ 22 ].…”

“…In addition to LAB, these four chitin containing diets also increased abundance of Actinomyces in gut microbiota in fish, with the highest abundance observed from full-fat meal diet. The enrichment of Actinomyces has previously been shown when salmon post-smolts [ 26 ] and rainbow trout [ 29 , 60 ] were fed BSF meal. Actinomyces are often identified as chitin degraders and might benefit from the presence of chitin [ 83 ].…”

Medical Image Recognition Technology in the Effect of Substituting Soybean Meal for Fish Meal on the Diversity of Intestinal Microflora in Channa argus

“…The soybean protein content in soybean meal is between 43.0% and 55.0%, and most of them are water-soluble proteins. Besides protein, they also contain other rich nutrients, which is a good dietary protein source for fish and monogastric animals [ 25 , 26 ]. Therefore, it is of crucially practical significance to explore the effects of soybean meal instead of fish meal on the intestinal microbial diversity of fish.…”

Overcoming Technical and Market Barriers to Enable Sustainable Large-Scale Production and Consumption of Insect Proteins in Europe: A SUSINCHAIN Perspective

“…Many of the feed products on the market today do not contain processed animal proteins (PAPs), which are approved to be used in fish feed. Insect protein has similar properties to PAPs and is a good, sustainable substitute [ 26 , 27 ] and an excellent source of energy and digestible amino acids for livestock. Since insect proteins were approved for use in aqua feed, European insect farmers have commercialized about 1000 tonnes of insect protein.…”