Ergot alkaloids

Ergot alkaloids are a large group of compounds produced by certain fungi belonging to the genus Claviceps and its relatives (e.g. the Neotyphodium endophyte fungi in grasses). Strains of C. purpurea, C. paspali and C. fusiformis.3 True ergots are sclerotia, or compact masses of hardened fungal mycelium containing nutrients reserves.1, 2 The role of sclerotia is to protect the fungus allowing it to survive adverse environmental conditions. Sclerotia appear like fruit bodies and replace the seed of some cereals and some grasses.3 The fungal spores are carried by the wind and upon germination on cereal or grass heads, form hyphae, which can penetrate and destroy the seeds, replacing them with a sclerotium.3, 4, 5 The sclerotia will subsequently produce conidiospores and sugar containing secretions to attract insects and favor further dispersion of spores to new hosts. In autumn, the sclerotia fall into the ground and overwinter until the following spring.3 Usually infection is favored by a cold winter followed by a wet spring. The fungus uses the nutrients from the plant for the development of the sclerotia and the production of the ergot alkaloids.3, 4 Ergots are present in the field and if the sclerotia are not eliminated during harvest, they can end up in food and feed.3

Ergot alkaloids are amides of the terpenoid indole derivate D-lysergic acid.5 All ergot alkaloid structures contain the tetracyclic ergoline ring and can be divided in different classes according to the substituents attached on the ergoline scaffold.5 The major classes are clavines (lysergic acids derivatives) and ergopeptides.4, 5

Toxicity

Pharmacological effects of ergots are due to their structural similarity to neurotransmitters such as noradrenaline, dopamine and serotonin.1, 2, 5 Effects of these chemicals are quite diverse. The ones with higher affinity to adrenergic receptor exert vasoconstrictive effects that can lead to nervous system or gangrenous syndromes.1, 2, 5 Some ergots show high affinity to the serotonin receptor and can cause serotonine syndrome that leads to neuropathological changes in the convulsive ergotism.1, 2, 4, 5 Other toxic effects of ergot alkaloids include digestive disorders (vomiting, diarrhea, feed refusal), reduced weight gain and abortion.1, 2, 4, 5

Regulation

Currently there is no regulation concerning the presence of ergots in feed in the USA. In the EU, the provisional maximum tolerated levels of ergot alkaloids in foodstuff are listed in table 1.1

Table 1. Regulation for ergot alkaloids in feedstuff in the EU.1
Undesirable substanceProducts intended for animal feedMaximum content in mg/kg (ppm) relative to a feed with a moisture content of 12 %
Rye ergot (Claviceps purpurea)

Compound feed for cattle (except dairy cattle and calves), sheep (except dairy sheep and lambs), goats (except dairy goats and kids), pigs (except piglets) and poultry (except young animals).0,02
Feed materials and compound feed containing unground cereals.1,000
References
  1. Jakubczyk D., Cheng J.Z., O'Connor S.E. (2014). Biosynthesis of the ergot alkaloids. The Royal Society of Chemistry DOI: 10.1039/c4np00062e
  2. Kainulainen K. (2003). Ergotism and ergot alkaloids – a review. Department of Medicinal Chemistry, Division of Pharmacognosy, Uppsala University.
  3. Krska R., Nährer K., Richard J. L., Rodrigues I., Schuhmacher R., Slate A. B., Whitaker T. B., (2012). Guide to Mycotoxins featuring Mycotoxin Risk Management in Animal Production. BIOMIN edition 2012
  4. Marin S., Ramos A.J., Cano-Sancho G., Sanchis V., (2013). Mycotoxins: Occurrence, toxicology, and exposure assessment. Food and Chemical Toxicology (60) 218-237.
  5. Zbib N., Repussard C., Tardieu D., Priymenko N., Domange C., Guerre P. (2015). Toxicity of endophyte-infected ryegrass hay containing high ergovaline level in lactating ewes. J. Anim. Sci. (93) 4098–4109.
  6. Commission regulation (EC) No 574/2011.