Vasoconstriction and Heat Stress Caused by Ergot Alkaloids and Fescue Toxins

XIN R TO IS O K C

Y M YC OF IX

T M

N M E A M N A G E

Vasoconstriction and heat stress caused by ergot alkaloids and fescue toxins

Competence Center Mycotoxin Risk Management Competence Center Mycotoxin Risk Management

Vasoconstriction and heat stress caused by ergot alkaloids and fescue toxins

Ergotism is one of the oldest known mycotoxicoses and the first documented epidemic of ergotism occurred in the middle ages when thousands of people died because of the “holy fire”.

rgot alkaloids (also named ergolines) ex- Classifications of ergot alkaloid producing fungi are ert toxic effects in all animal species, and shown in Table 1. the most prominent toxic signs can be attributed to the interaction of ergot al- The main groups of natural ergot kaloids with adrenergic, serotinergic and alkaloids are: dopaminergic receptors. • The clavines – e.g. agroclavine Information on the chemical and toxicological prop- • The lysergic acids Eerties of individual ergot alkaloids is too limited at the • The lysergic acid amides – e.g. ergonovine (ergo- present time for their selection as individual marker metrine, ergobasine), ergine toxins when it comes to monitoring the extent of con- • The ergopeptines – e.g. ergovaline, ergotamine, er- tamination. This means that neither the total alkaloid gocornine, ergocristine, ergosine, ergocryptine content, nor a single alkaloid can be recommended as reliable indicators of the potential adverse effects to live- The ingestion of contaminated feedstuffs by the ani- stock associated with the ingestion of ergot contaminat- mals can have several sources ranging from contaminated ed feeds. Alkaloids have different and dose-dependent farm equipment to contaminated seed line and feeding receptor selectivity (binding affinity). Consequently, contaminated hay or silage. Therefore, good agricultural the biological effects of the various complex mixtures practices that limit contamination along with feeding to which animals are exposed to, remain unpredictable. compounds that have the capacity to bind these toxins The term ergot alkaloid refers to a diverse group of are needed to reduce or eliminate the harmful effects. about forty different toxins which are formed by Clavi- These selected substances bind ergot alkaloids in the ceps spp. on grains (rye (see Figure 1), triticale, corn, gastrointestinal tract, reduce their bioavailability and wheat, barley, oats, millet, sorghum and rice) and by increase their excretion as an adsorbent-toxin complex, fungal endophytes such as Neotyphodium spp. in grass- thus helping control the negative impacts of these my- es, particularly tall fescue and perennial ryegrass, which cotoxins. adversely affects the health and productivity of livestock. Ingestion of endophyte toxins in grasses, even at This fungus produces the ergot responsible for the ergot sub-clinical amounts is of concern in animal produc- alkaloid group of mycotoxins and parasitizes the seed tion. Perennial ryegrass endophytes (Neotyphodium lolii) heads of plants at the time of flowering. together with the neurotoxin lolitrem B and the vaso-

Table 1. Classification of the main ergot alkaloid producing fungi Major classes Fungi species Mycotoxins Claviceps C. purpurea Ergot alklaloids: clavines, lysergic acid, lysergic acid amids, ergo- C. fusiformis peptines C. paspali C. africana Neotyphodium (form. N. coenophialum Tall fescue toxins (endophyte toxins): ergot alkaloids, lolines, Acremonium) peramine N. lolli Tall fescue toxins (endophyte toxins): lolitrems, peramine, ergot alkaloid (ergovaline)

2 Competence Center Mycotoxin Risk Management

Figure 1. Hybrid rye contaminated with ergots

Table 2. Biochemical criteria to diagnose potential ergot alkaloid toxicity Table 3. Threshold levels of ergovaline and lolitrem B in the diet able to produce a clinical disease Ergovaline Animal Toxic Sub-toxic Ergovaline (ppb) Lolitrem B (ppb) Urine lysergol:creatinine Sheep >7.0 <4.0 Cattle 400-750 1.800-2.000 Cattle >4.0 <2.5 Sheep 500-800 1.800-2.000 Ergovaline intake Sheep >0.08 0.03 (mg/kg LW0.75) Horses* 300-500 Not determined Cattle >0.11 0.03

Pasture ergovaline Sheep >0.9 0.3 * Except for mares in the last 60 to 90 days of pregnancy, when (mg/kg DM) Cattle >0.9 0.3 the threshold is zero. Mg/kg LW0.75: milligrams per kilogram of animal live weight Mg/kg DM: milligrams per kilogram of dry matter intake

constrictor ergovaline are responsible for, among others, including convulsions, abortions and death, reduced hypersensitivity in ruminants, impaired heat stress rec- prolactin secretion and consequently agalactia have been ognition, and vasoconstriction. reported as major adverse eff ects in animals. Due to the Plant toxins are a chemical defense of plants against fact that animals are exposed to a multiplicity of alka- herbivores. Endophytic toxins in grasses include ergot loids when consuming endophyte-infected tall fescue, alkaloids in tall fescue and tremorgens (e.g., lolitrem a combined alkaloid eff ect has been suggested by Klotz B) in perennial ryegrass. Perennial ryegrass endophyte et al. (2008). Chronic exposure to moderate amounts (Neotyphodium lolii) alkaloids are frequently present in of ergot alkaloids results in reduced weight gain, low pastures containing the neurotoxin lolitrem B, together reproductive effi ciency, including decreased conception with the vaso-constrictor ergovaline, at levels associated rates, decreased circulating progesterone, and reduced with ryegrass staggers, heat stress, ill-thrift and lowered signs of estrus. milk production. It has been shown that some of the physiological processes such as fertility may be lowered Experiments conducted in New Zealand indicate following ingestion of alkaloids produced by Neotypho- that cattle are slightly less susceptible to ergovaline tox- dium endophytes. icity than sheep with respect to live weight gain suppres- sion (Table 2). Toxicity Animals can be exposed to complex mixtures of er- Th reshold levels of ergovaline and lolitrem B have got alkaloids in many typical animal agriculture produc- been established for cattle, sheep and horses (Table 3). tion systems. Th is exposure results from the fact that Th ese levels, however, refer to the level of toxin in the the kinds of alkaloids present and their levels can vary total diet, not in single feed components. widely, depending on the fungal strain, the host plant and environmental conditions, being impossible to relate Conclusion the exposure to individual toxins. Th e chemically diverse Th e use of high quality feedstuff s to reduce toxicosis group of ergot alkaloids has been shown in vasoconstric- of ergot alkaloids in livestock is the fi rst step in avoiding tion symptoms, being responsible for heat intolerance problems they can cause, but to totally protect animals as well as necrosis of ears, tails and often hooves. Other from the increasing risk of ergot alkaloid poisoning, a symptoms such as gangrenous changes, neurotoxic signs mycotoxin risk assessment is recommended.

ART_No23_MYC_R_EN_0514_KPE