FEATURE
THE UNSEEN
A
nyone with a background in life sciences will at sometime have come across Aflatoxin, a metabolite produced by the Aspergillus genus of moulds which has been well documented as the cause of fatal poisoning in both farm animals and humans following ingestion of contaminated food, with peanuts and maize being the most common route of uptake. Perhaps less widely known is the abundance and variety of similar so-called mycotoxins and their often less dramatic but nevertheless detrimental effects on organisms, which have ingested them. Animal nutritionists understand well the toxic actions of these fungal metabolites, some examples of which are included in the table below. Whilst much of the research to date has focussed on the impact to farm animals from mycotoxins which they have ingested through their feed, some interesting and illuminating studies have emerged over the last decade into the effects that these toxins can have on cultured fish which have been exposed to contaminated feed. By way of example Hooft et al (2010) demonstrated a significant reduction in appetite, weight gain and feed efficiency in Rainbow trout which had been exposed to DON (deoxynivalenol , a trichothecene mycotoxin found in wheat, barley oats and maize). He presented these results at the International Symposium on Fish Nutrition in Molde in 2012 concluding that Rainbow trout are highly sensitive to DON even at levels as low as 1 ppm. So how can fish farmers defend their stocks against the stealth threat posed by mycotoxins that occur as contaminants in feed?
ENEMY
Recently, PHARMAQ UK has entered into an arrangement with an exciting and innovative French company, Olmix, who have developed a novel and naturally derived additive that can be applied to feeds as a protection against unwanted contaminants. Olmix’s unique solution to this problem has been developed by combining specific extracts of seaweeds with Montmorillonite clay (Amedéite®) sourced locally to their premises in Brittany. The innovative combination of algal extracts and this fine clay creates a product that is extremely effective in the adsorption of mycotoxins. The product, known as MTX+, already has a ten-year track record in terrestrial livestock Mycotoxin Aflatoxin B1
by Chris Mitchell and Rob Sinnott
of global crops estimated to be currently affected by mycotoxins and increasing pressure to include more grain derived material in fish diets, greater attention will need to be focussed on the raised potential for microbial contamination by mycotoxin producing organisms in fish diets. This is a challenge not only because these molecules are quite difficult to detect, but also because they are robust and can persist as contaminants even if the source mould has been removed. In addition it has been suggested that because mycotoxin production by moulds is often a mechanism of defence, the very interventions which are applied to limit mould infestation of grains in storage (heat,
Toxic activity Carcinogenic / immunosuppressive
Ochratoxin A
Carcinogenic / nephrotoxic / immunosuppressive
Fumonasin B1
Carcinogenic / neurotoxic
Zearalenone
Estrogenic
Trichothecenes dermatoxic T-2 toxins immunosuppressive
production where demand continues to grow. By adsorbing mycotoxins in the intestine MTX+ significantly lowers the availability of these molecules for absorption into the animal. Thus intestinal integrity is preserved and immunosuppression, a hallmark of mycotoxin toxicity, is avoided. Its application to aquaculture was heralded in 2011 in a trial on farm-raised tilapia in Viet Nam. As well as a modest improvement in FCR, fish that had MTX+ added to their diet showed an 8.5 percent improvement in daily weight gain over the control group. Early days indeed but with 25 percent
humidity reduction and some fungicides) can actually encourage the production of these metabolites! Through the inclusion of a naturally derived and formulated mycotoxin binder such as MTX+ into the feed of fish, especially during their early life history, health managers can at least be sure that they are giving the stocks under their care the best start, free of these pernicious stealth toxins. For more nformation on how MTX+ might contribute to your stock health management strategy please contact Chris Mitchell on +44 7769 330540 or chris.mitchell@pharmaq.no
12 | INTERNATIONAL AQUAFEED | September-October 2014