A novel bacterial solution Improving resistance of early stages of Rainbow Trout (Oncorhynchus mykiss) with a novel bacterial solution
Alexandre Brame, Stephane Frouel and Maxime Hugonin report on a field trial run in France to evaluate the potential of a microbial solution to beneficially modulate microbiome in trout farming system and improve resistance and performance from eggs hatching to early juveniles’ stage of rainbow trout Oncorhynchus mykiss.
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mong the farmed aquatic species, rainbow trout is one of the most important. Some experts have projected that the world's consumption of rainbow trout will hit 950,000 metric tonnes (mt) annually in the first quarter of 2020 alone. The majority of this volume will be provided by aquaculture, with global sales volume of farmed trout expected to reach roughly 830,000 tonnes (t). The continued relatively high cost of salmon has seen rainbow trout establish itself as a cheaper alternative fish, offering many of the same health benefits. The specialists predict a compound annual growth rate for worldwide rainbow trout market of approximately five percent over the next 10 years. However, diseases are a primary problem
by Alexandre Brame, Innovation Manager, Nolivade, Stéphane Frouel, Aquaculture Project Manager and Maxime Hugonin, Aquaculture Product Manager, Mixscience, France
in trout aquaculture and can severely impact its economic progression in many countries. The development of a fish disease is the result of the interaction between pathogens, hosts and the environment. Numerous studies have reported that water treatments may be an indirect driver in shaping the bacterial communities of the environment, skin, gills and gastrointestinal tract, commonly referred to as the ‘microbiomes’, of aquatic animals. These microbes are believed to play important roles in host development, immunity, digestion and nutrition. On the contrary, deleterious bacteria may play inverted role. The diseases encountered in rainbow trout include: those caused by bacteria (Aeromonas spp., Yersinia spp., bacterial kidney disease, Flavobacterium spp., …), parasites (Gyrodactylus, Chilodonella, Trichodina, Epistylis, Trichophrya, Ichthyopthirius, Ichtyobodo, proliferative kidney disease, amoebic gill infestation, Coleps), fungi (Saprolegnia), and viruses (infectious pancreatic necrosis, viral hemorrhagic septicemia, and infectious hematopoietic necrosis). Should a disturbance occur that causes an imbalance, or dysbiosis, in the commensal microbiome, the fish may be more vulnerable to pathogenic infection. Indeed, the gastrointestinal tract, in addition to the skin, gills and any 30 | June 2020 - International Aquafeed
modification of environmental water, are known to be the major routes of entry for potentially pathogenic microorganisms in fish. The management practices designed to
Figure 1: Statistical difference of main pathogenic bacteria abundance (expressed as %) between Control group (CTRL) in pink and Experimental group with Nolivade microbial solution (EXP) in blue