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Equine fescue toxicosis: signs and solutions.
Abstract: Gravid mares grazing endophyte-infested (E+) tall fescue exhibit increased gestation lengths, agalactia, foal and mare mortality, tough and thickened placentas, weak and dysmature foals, increased sweating during warm weather, reduced serum prolactin and progesterone, and increased serum estradiol-17 beta levels. Also, E+ tall fescue hay is less digestible than endophyte-free (E-) hay. Unlike many other species, horses consuming E+ tall fescue do not exhibit increased body temperature. Young horses consuming only E+ pasture do not gain as well as those consuming E- pasture. There is little difference in gain when the pasture is supplemented with enough concentrate to meet NRC requirements for growth. Neither selenium injections nor supplementing with corn at 50% of the NRC requirements for energy reduces the effects of toxic tall fescue on reproduction and lactation in gravid mares. It seems that the alkaloids of E+ tall fescue are serving as D2 dopamine receptor agonists. This activity would explain their prolactin-lowering effect. Domperidone, a dopamine receptor antagonist, is effective in preventing the signs of tall fescue toxicosis in horses without neuroleptic side effects.
Publication Date: 1995-03-01 PubMed ID: 7608025DOI: 10.2527/1995.733899xGoogle Scholar: Lookup The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Journal Article
- Review
Summary
This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.
The research article discusses the negative impact of a toxic grass called endophyte-infested (E+) tall fescue on pregnant horses and their foals, as well as possible solutions to counteract these effects.
Signs and Symptoms of Equine Fescue Toxicosis
- The research found that when pregnant mares graze on fields of E+ tall fescue, they exhibit a variety of adverse health symptoms. These include an extended gestation period, lack of milk (agalactia), high mortality rates in both mares and foals, excessively rough and thick placentas, and the birth of weak and slow-to-develop (dysmature) foals.
- Horses grazing on E+ tall fescue exhibited increased sweating, decreased levels of serum prolactin and progesterone, and an increase in serum estradiol-17 beta levels.
- Interestingly, unlike many other species, horses consuming E+ tall fescue do not exhibit an elevated body temperature.
Effects of E+ Tall Fescue Hay on Digestibility and Growth
- The study also pinpointed that E+ tall fescue hay is not as efficiently digested by horses as endophyte-free (E-) hay.
- Young horses solely consuming E+ pasture had worse weight gain compared to counterparts consuming E- pasture. However, when the pasture was supplemented with additional nutrient concentrates meeting the NRC’s requirements for growth, there was little difference in weight gain.
Ineffective Solutions and Potential Causes
- Attempts to mitigate the effects of toxic tall fescue on the reproduction and milk production of pregnant mares using selenium injections or supplementing with corn were unsuccessful.
- The adverse symptoms are suspected to arise from the alkaloids present in E+ tall fescue acting as D2 dopamine receptor agonists, which would explain their effect in lowering prolactin.
Potential Solution for Equine Fescue Toxicosis
- The research found that Domperidone, a dopamine receptor antagonist, is effective in preventing the signs of tall fescue toxicosis in horses without causing side effects commonly associated with drugs that affect the central nervous system (neuroleptic side effects).
Cite This Article
APA
Cross DL, Redmond LM, Strickland JR.
(1995).
Equine fescue toxicosis: signs and solutions.
J Anim Sci, 73(3), 899-908.
https://doi.org/10.2527/1995.733899x Publication
Researcher Affiliations
- Clemson University, SC 29634-0361, USA.
MeSH Terms
- Acremonium / isolation & purification
- Acremonium / metabolism
- Animal Feed / poisoning
- Animals
- Body Temperature / physiology
- Domperidone / therapeutic use
- Ergot Alkaloids / metabolism
- Ergotism / physiopathology
- Ergotism / therapy
- Ergotism / veterinary
- Estradiol / blood
- Female
- Horse Diseases / physiopathology
- Horse Diseases / therapy
- Horses
- Poaceae / microbiology
- Pregnancy
- Pregnancy Complications / physiopathology
- Pregnancy Complications / therapy
- Pregnancy Complications / veterinary
- Progesterone / blood
- Prolactin / blood
- Weight Gain / physiology
References
This article includes 89 references
Citations
This article has been cited 11 times.- Haimon MLJ, Poole RK, Newsome MA, Brown AR, Dudley H, Poole DH. Examining the long-term impacts of ergot alkaloids on fetal heifer development and subsequent growth and reproductive performance. J Anim Sci 2024 Jan 3;102.
- Lee K, Missaoui A, Mahmud K, Presley H, Lonnee M. Interaction between Grasses and Epichloë Endophytes and Its Significance to Biotic and Abiotic Stress Tolerance and the Rhizosphere. Microorganisms 2021 Oct 20;9(11).
- Poole RK, Poole DH. Impact of Ergot Alkaloids on Female Reproduction in Domestic Livestock Species. Toxins (Basel) 2019 Jun 21;11(6).
- Klotz JL, McDowell KJ. Tall fescue ergot alkaloids are vasoactive in equine vasculature. J Anim Sci 2017 Nov;95(11):5151-5160.
- Klotz JL. Activities and Effects of Ergot Alkaloids on Livestock Physiology and Production. Toxins (Basel) 2015 Jul 27;7(8):2801-21.
- Penagos Tabares F, Bedoya Jaramillo JV, Ruiz-Cortés ZT. Pharmacological overview of galactogogues. Vet Med Int 2014;2014:602894.
- Dearing MD. Temperature-dependent toxicity in mammals with implications for herbivores: a review. J Comp Physiol B 2013 Jan;183(1):43-50.
- Fayrer-Hosken R, Stanley A, Hill N, Heusner G, Christian M, De La Fuente R, Baumann C, Jones L. Effect of feeding fescue seed containing ergot alkaloid toxins on stallion spermatogenesis and sperm cells. Reprod Domest Anim 2012 Dec;47(6):1017-26.
- Bacetty AA, Snook ME, Glenn AE, Noe JP, Nagabhyru P, Bacon CW. Chemotaxis disruption in Pratylenchus scribneri by tall fescue root extracts and alkaloids. J Chem Ecol 2009 Jul;35(7):844-50.
- Haarmann T, Rolke Y, Giesbert S, Tudzynski P. Ergot: from witchcraft to biotechnology. Mol Plant Pathol 2009 Jul;10(4):563-77.
- Panaccione DG, Johnson RD, Wang J, Young CA, Damrongkool P, Scott B, Schardl CL. Elimination of ergovaline from a grass-Neotyphodium endophyte symbiosis by genetic modification of the endophyte. Proc Natl Acad Sci U S A 2001 Oct 23;98(22):12820-5.
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