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SALMONIDS
THE USE OF PREBIOTICS IN SALMONID DIETS Natural alternatives for improving production by Fernando Roberti, Biorigin
ish production has been gaining increasing importance in the protein market and in the animal nutrition sector. Estimates indicate that it will reach 160 million tonnes by 2030, with an increasing participation of aquaculture1. In this context, for supporting the intensification of the production, which on one hand requires increasingly revenues, but on the other predisposes to disease outbreaks, the use of functional compounds becomes essential. To achieve an economically viable aquaculture, it is fundamental to maximise nutrient digestibility and retention, feed conversion rate, dietary nutrient balance, and minimising fish mortality in antibiotic-free conditions through the development of health-promoting diets. In this context, the inclusion of prebiotics into fish diets plays a very important role for these results to be reached.
by using a component that resists the passage along the gut during digestion and mimics the specific carbohydrates groups of intestinal cells4. Moreover, MOS are also a fermentation substract for beneficial bacteria which are able to produce organic acids. This fermentation, in addition to promoting the growth of these beneficial bacteria populations, leads to an acidification of the intestinal environment due to the acid production. Importantly, some of these acids are used as the major energy sources by some gut cells5, helping to maintain the intestinal integrity. Together, all these benefits generate a healthy environment, which will favor nutrients digestibility and absorption. To reach these benefits, however, it is important to select a good MOS product that presents the following characteristics: high mannan content, high mannan exposure – obtained from a suitable production process – which ensures a good pathogens adhesion, and a high total carbohydrates content for fermentation purposes.
Prebiotics
Beyond the benefits to performance, maintaining good intestinal health is particularly important since many infectious diseases initiate from the colonisation of the gut mucosa by pathogens, and the efficiency of the intestinal barrier against this process depends on the intestinal integrity and on the balance of comensal bacteria6. In addition, the more intact the intestinal barrier, the more pathogens will be avoided to translocate over stressing conditions, reducing the risks of the development of systemic frames.
Prebiotics are non-digestible compounds able to modulate gut microbiota and to selectively stimulate the growth of beneficial bacteria2. Among prebiotics, mannanoligosacharides (MOS) from the yeast Saccharomyces cerevisiae have been widely researched and applied in animal nutrition. The main described effects of MOS are related to pathogen colonisation blocking, alongside growth and feed conversion improvement. The use of MOS as a pathogen colonisation blocker evolves from the concept that some sugars as mannose could be used as inhibitors of pathogen adhesion to intestinal cells3. Therefore, the objective of including MOS in aquaculture feeds is to reduce intestinal attachment of pathogenic bacteria
Importance of intestinal health for fish
Trial with rainbow trouts
A study* performed in a semi-intensive farm located in Mazandaran, Iran, evaluated the effects of the dosages 0, 0.1, 0.25 and 0.4 percent of MOS (ActiveMOS, Biorigin, Brazil)
40 | May | June 2016 - International Aquafeed