Tackling ergot contaminations from day one
Ergot is a term that describes the sclerotia (also known as ergot bodies) produced by fungi in the Claviceps genera, particularly C. purpurea. Toxic alkaloids produced by the fungi are stored in the ergot bodies. The incidence of ergot infection of grains and its severity vary from year to year.
The incidence of ergot infection of grains and its severity vary from year to year. Ergot is most prevalent in years with increased moisture available at the soil surface in spring and early summer or with wet weather prevailing during the flowering stage of cereal crops (Pearse, 1999). Several cereal grain species (including rye, wheat, triticale, barley, oats and others) are vulnerable to ergot infection, producing ergot bodies. Ergot bodies can be removed during seed screening and cleaning processes. If not removed, their presence in these grain screenings still present a health risk for livestock. To limit this risk there are currently regulations for the allowed quantities of ergot bodies in grain and feed (table 1).
The actual content of ergot alkaloids depends on their concentration in the ergot bodies. EFSA has reported a strong correlation between the content of sclerotia and the levels of ergot alkaloids (coefficients ranged between 0.806 for rye grains and 0.972 for triticale grains). However, in the same report, the absence of sclerotia did not exclude the presence of Ergot alkaloid (EA). However some samples with no sclerotia identified showed measurable levels of Ergot Alkaloids (EA’s).
Contamination levels and effects
The effects of ergot toxicity vary among different livestock species. Poultry appears to be able to handle higher dietary alkaloid concentrations than ruminants or swine (Thompson, 2016).
Typical clinical symptoms of ergot poisoning are vasoconstriction, which may progress into gangrene, disruption of reproduction, abortion, neurotoxic signs including feed refusal, dizziness and convulsions, agalactia and adverse effects to the cardiovascular system. Normally these symptoms are associated with high contaminations, above regulations or recommendations limits.
There are some ergot reports of concentrations close to regulations already showing a detrimental effect. In a swine trial where the animals were exposed for 28 days to doses with concentrations close to the EU regulations (1.2 and 2.5 gr sclerotia/kg feed), the results were remarkable. The animals that were fed with a higher dosage showed a decrease in feed intake in the second week. The animals that were fed with a lower dosage reported a reduction in the last 14 days of the experiment. No clinical signs of acute toxicity were reported but different organs were affected. In the liver you could see an alteration of the tissue, including development of inflammatory infiltrates. In the jejunum, a reduced villi height and increased damage to the epithelium (Maruo et al., 2018).
Other studies (Oresanya et al., 2003) reported a dose response reduction in ADFI in the last week of a 28 days trial with weaned pigs fed feed containing ergot concentrations ranging from 0.05 to 1.00% of the diets. The reduction in feed intake has been linked to the aromatic properties of ergot alkaloids (Whittemore et al., 1977). Because of several reports of detrimental effects with ergot contamination close to regulation limits, different authors have suggested a more practical table of recommendations taking in consideration the actual alkaloid content rather than ergot bodies.
Contamination levels and effects
At feed mill level, the recommendation to avoid contamination by ergot is the same as any mycotoxin contamination. A good quality control of incoming raw materials that stresses out the importance of a good sampling protocol. Further down the feed manufacturing process some techniques that can reduce the risk include grain cleaning methods (i.e. scalpers, shaker decks) that remove impurities, or specific grain cleaning equipment such as gravitational separators and color sorters. At farm level, the recommendation is to remove the affected feed.
As with other mycotoxin contamination, the use of mycotoxin binders is an alternative. While there is very limited reports of in vivo studies testing mycotoxin binders, in vitro binding efficacy, similarly to other mycotoxins, can give an indication of the potential capacity of a product to reduce the effects of ergot contamination when fed to farm animals. Therefore, such in vitro binding tests are very useful for making a differentiation between the different commercial toxin binders available in the market and to select a binder that can bring a real added value in tackling ergot contaminations in animal feed.