‘Plant Diseases are Shifty Enemies’


plant pathologist Elvin C. Stakman By Jane Brooks


Mycotoxins are a growing concern as they contain toxic properties which impact on feed quality, public health and performance. Found worldwide on virtually all crops, mycotoxins are toxic secondary metabolic products of fungi. The term mycotoxin originated in 1962 when an English producer


lost 100,000 turkey poults to a mystery disease. Named ‘turkey X disease’ its cause was linked to peanut meal contaminated with secondary metabolites from Aspergillus flavus (aflatoxins). In fact last year PepsiCo recalled a brand of peanuts from multiple


countries due to higher than permitted levels of aflatoxin. According to PepsiCo the product was sent to and sold in Netherlands, Belgium, Luxembourg, United Kingdom and Republic of Ireland. The company said analyses showed some cans of Duyvis peanuts


might contain aflatoxin B1 levels exceeding the European limit, but that consumers weren’t at risk from short-term exposure. In 2016 a RSA Insurance Group white paper reported that in Europe


an average 500 human food chain product recalls are initiated annually, with approximately 130 classified ‘severe’ as per RASFF (Rapid Alert System for Food and Feed). Main recall causes are contamination of the products with


allergens (30%), foreign bodies (20%), unauthorised substances (9%), mycotoxins (9%), food additives and flavouring (9%), heavy metals (6%), biocontaminants (5%), biotoxins (4%) and industrial contaminants (4%).


Risk reduction Steps can be taken to reduce mycotoxin contamination but it’s impossible to eliminate the risk. Climatic conditions impact on the presence of mycotoxins. Maximising plant performance and reducing stress can substantially decrease mycotoxin contamination. Good agricultural practice pre- and post-harvest, during handling,


storage, processing and distribution of cereals can reduce and minimise mycotoxin contamination. European harvest samples submitted to the Alltech 37+®


mycotoxin


analytical services laboratory in 2018 showed high levels of mycotoxins, particularly deoxynivalenol (DON), fusaric acid and fumonisin in areas of excessive rainfall during flowering and pollination or late-season rain after heat and drought stress. This situation occurred for grains and forages alike. Dr. Max Hawkins, global technical support with the Alltech®


Mycotoxin Management team explained that mycotoxins thrive in changeable conditions, with lack of rain, excessive rainfall or, sometimes, one after the other causing a perfect storm of contamination. “The extreme weather events we’ve seen this year around the world have led to an increased occurrence of mycotoxins in many countries.” European grass silage samples showed a 100% occurrence of


fusaric acid, while maize silage showed a 100% occurrence of type B trichothecenes, both of which can be detrimental to rumen health and function. Maize silage has a longer growing season than many grains and uses the whole plant, which leads to more mycotoxins in the crop.


PAGE 18 MARCH/APRIL 2019 FEED COMPOUNDER


Dr. Hawkins said the biggest threat to the wheat crop and barley in


Europe is mycotoxin type B trichothecenes, found in more than 56% of wheat samples and 70% of barley samples. Results from Croatia, Serbia and Spain show a 100 per cent occurrence of type B trichothecenes. On average, corn samples showed the presence of three different


mycotoxins, mostly coming from fumonisins, which affect the growth of pigs. Mycotoxins are seldom found in isolation and multiple-consumption can present a greater risk to animal performance and health.


UK grown cereals Back in 2017 an AHDB project looked at the occurrence of key contaminants in in UK-grown wheat, barley and oats and their co- products. The project covered samples from the 2012, 2013, 2014 and


2015 harvests intended for use in the milling, malting and animal feed industries. Samples were collected post-harvest and after storage of up to six months. The contaminants selected were pesticides, growth regulators,


desiccants, mycotoxins (Fusarium toxins, Ochratoxin A and ergot alkaloids), heavy metals, dioxins and chlorates. The overwhelming majority of samples complied with legal and


guideline limits. Levels of applied storage pesticides, growth regulators and desiccants were all within legal limits and levels didn’t vary significantly from season to season. Looking further at the results, the storage mycotoxin, Ochratoxin


A was generally detected only at low concentrations, with mean and median values largely being determined at levels at, or just above the LOQ (0.1 μg/kg). This demonstrated that mould growth and toxin synthesis were


adequately controlled by suitable storage conditions. Levels of Fusarium mycotoxins, which in previous surveillance projects have showed significant seasonal variations, increased from 2011 to 2012 but largely declined from 2012 to 2015. Ergot alkaloids were generally determined at very low levels, the vast majority of samples having a median value below the method LOQ. Feed mills are generally successful at managing mycotoxin


challenges, however the best way to control mycotoxin is at source. The use of a break crop, such as oilseed rape, root crops, vegetables or grass in a cereal rotation helps to clean soils of fungal spores. But across Europe break crop use is declining, due in part to cropping and financial constraints and the loss of neonicotinoids in the case of OSR. Additionally as minimum tillage and zero tillage systems gain in


popularity and crop-residues aren’t buried by ploughing there’s a greater risk of fungal spores colonising crop residue. It’s a tricky balance because minimal soil disturbance benefits organic soil matter and can be more cost effective. Primary agricultural production is mycotoxins’ main point of entry


into the food chain and every effort needs making to keep fungi out of the growing crop prior to harvest and during drying. It’s the farmers’ responsibility to minimise the risk, through cultural methods and a robust fungicidal crop protection programme. The milling industry bears the brunt of food scares if mycotoxins get


through the milling process and end up in a retailers’ product. Regulations currently exist with legal and guidance (non-regulatory) limits for certain mycotoxins in animal feed. Consumers are increasingly aware of mycotoxins risk to the health


of their livestock or pets. In the equestrian world BETA (British Equestrian Trade Association) is undertaking research looking at acceptable levels of mycotoxins in equine diets, raw materials and feedstuffs, to provide guidance to their members.


Comment section is sponsored by Compound Feed Engineering Ltd www.cfegroup.com


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