Ergot Alkaloid Effects on Livestock Physiology

Ergot alkaloids are a class of mycotoxins produced by certain fungal endophytes in forage grasses and by Claviceps species in cereal grains. In grazing livestock, chronic exposure induces a syndrome known as fescue toxicosis, characterised by persistent vasoconstriction, heat intolerance, suppression of prolactin secretion and depressed feed intake. At the vascular level, alkaloids bind to serotonergic and adrenergic receptors in peripheral and reproductive blood vessels, reducing blood flow to extremities and reproductive organs. Endocrine disruption further diminishes growth rates, alters hair coat shedding and impairs reproductive cyclicity, leading to reduced fertility and offspring weight. Alterations in rumen and hindgut microbial communities have also been observed, suggesting that host–microbiome interactions modulate individual tolerance. The net result is significant global production losses through lowered weight gains, impaired thermoregulation, reproductive failure and increased susceptibility to environmental stress. Mitigation strategies under investigation include the use of non-ergot-producing endophyte varieties, legume interseeding to supply vasorelaxant isoflavones and nutritional management to support detoxification pathways.

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Ergot Alkaloid Effects on Livestock Physiology publication trend

The graph below shows the total number of articles in ergot alkaloid effects on livestock physiology across all publications each year (not limited to Nature Index journals).

Technical terms

Endophyte: A fungus living within plant tissues that can synthesise ergot alkaloids, notably in tall fescue.

Fescue toxicosis: The syndrome resulting from chronic consumption of endophyte-infected forage, marked by vasoconstriction, hyperthermia, reduced feed intake and reproductive dysfunction.

Ergovaline: The principal ergopeptine alkaloid produced by endophyte-infected tall fescue, responsible for most vasoconstrictive effects.

Vasoconstriction: The narrowing of blood vessels due to smooth muscle contraction, leading to reduced blood flow and impaired thermoregulation and reproductive perfusion.

References

1. Behavioral and Physiological Alterations in Angus Steers Grazing Endophyte-Infected Toxic Fescue during Late Fall. Toxins (2023).
2. Impact of Ergot Alkaloids on Female Reproduction in Domestic Livestock Species. Toxins (2019).
3. Activities and Effects of Ergot Alkaloids on Livestock Physiology and Production. Toxins (2015).
4. Interaction of ergovaline with serotonin receptor 5-HT2A in bovine ruminal and mesenteric vasculature1. Journal of Animal Science (2018).
5. Ergot alkaloids induce vasoconstriction of bovine uterine and ovarian blood vessels. Journal of Animal Science (2018).
6. Fescue toxicosis and its influence on the rumen microbiome: mitigation of production losses through clover isoflavones. Journal of Applied Animal Research (2018).
7. Beef cattle that respond differently to fescue toxicosis have distinct gastrointestinal tract microbiota. PLOS ONE (2020).