Heat stress in ruminants can be the result of ingesting toxins such as ergot alkaloids, produced by common endophytes found in many plant species and by fungi contaminating grains. Ergots alkaloids are vaso constrictors and can cause most serious disorders such as tall fescue and perennial ryegrass toxicoses. When a high ergovaline level in feed, coincides with high ambient temperature, its impact is amplified.
(1) Cawdell-Smith AJ, Bakau WJK, Scrivener CJ, Reed KFM, Blaney BJ, Bryden WL (2007) Ergot toxins and Animal Disease in Australia. pp. 519-524. In: Poisonous Plants: Global Research and Solutions (eds. KE Panter, TL Wierenga, JA Pfister) CABI Publishing, Wallingford, UK.
(2) Reed KFM, Webb Ware J (2012) Management of perennial ryegrass endophyte toxicosis, pp52. Meat and Livestock