Mycotoxins: The Basics about Fusariotoxins
BIOMIN GmbH, Herzogenburg, Austria.Pig feed plays a key-role in maximizing the animal’s genetic potential, representing 60 to 80% of total production cost. There are many substances that have to be considered as contaminants in animal feedstuffs. Mycotoxins are naturally occurring compounds in feedstuffs which can have deleterious health effects to animals and humans due to the consumption of animal products. They are a problematic issue in animal feed industry, since about 25% of world’s food crops are contaminated with these toxic substances. Fusarium sp. mycotoxins are the most prevalent mycotoxin-producing fungi occurring in Europe due to their preference for the weather conditions existing in this region.
Fusariotoxins
Fusariotoxins is the common name given to mycotoxins produced by fungi of the Fusarium sp. genus.
These mycotoxins are produced mainly on the field before harvest by a large and complex mould family with species adapted to a wide range of habitats and, although having a special affinity for moderate climates, they contaminate crops all over the world. This fact makes fusariotoxins probably the most economically significant grain mycotoxins worldwide. The most important mycotoxins being produced by Fusarium sp. are trichothecenes (ex.: DON, T-2 toxin), zearalenone and fumonisins. The Fusarium species of most concern are those that produce mycotoxins in wheat, maize, rice, barley, oats and other cereal grains that are used in animal and human diets.
Table 1 - Most important mycotoxins produced by Fusarium spp. and their occurrence in Europe.
Feeding cereals to pigs
Feed must provide the correct nutrient requirements for a maximum efficiency regarding reproduction and growth while generating a food. Over the past few years there have been scares related to food safety such as BSE and dioxins leading to the prohibition with animal protein sources, such as meat meal, feather meal, poultry meal, hoof meal and blood meal and although feeding of fish meal in small percentages is allowed, the importance of plant protein sources has increased enormously. No matter what the origin of the feed is - bought feed mixture or on-farm mixed feed - rations should provide animals a correct quantity of digestible energy (DE), proteins, minerals and vitamins.
Cereal grains account from 55 to 70% of the total feed mixture, representing the main source of energy for pigs. Wheat, barley and maize are typically included in pig feed due to their high DE value, therefore being a major source of mycotoxins contamination.
Although many Fusarium species can infect cereal grains, Fusarium graminearum is the major causal agent of head scab of small grains and of red ear rot in maize. There are two typical routes of entry of Fusarium graminearum infection in cereals: 1) The spores are already on the field at the time of silks’ emergence thus infecting the silk channel; 2) Birds, insects or extreme weather conditions are able to cause damage to the kernels before their hardening thus providing an opportunity for fungal damage.