The impact of endophyte-infected fescue consumption on digital circulation and lameness in the distal thoracic limb of the horse.
Abstract: This experiment was conducted to evaluate if consumption of endophyte-infected fescue alters digital circulation in the distal thoracic limb of the horse and to assess if soundness of the hooves of horses is affected by consumption of endophyte-infected fescue. Twelve American Quarter Horses (mean initial BW 459 ± 31 kg), 6 mares and 6 geldings, were used in this 90-d study that comprised high-endophyte (E+) and low-endophyte (E-) treatment groups. Fescue seed was integrated into the E+ diet at a rate sufficient to bring total ergovaline to 200 μg/kg, and endophyte-free fescue seed was incorporated into the E- diet from d 0 to 90. From d 30 to 60, native prairie hay was replaced with high- or low-endophyte fescue hay, bringing total dietary ergovaline to 280 μg/kg (E+) and 18 μg/kg (E-). From d 61 to 90, fescue seed was ground to decrease particle size. On d 0, 30, 60, and 90, Doppler ultrasonography and thermographic imaging were used to measure the diam. of the medial palmar artery, velocity of blood flow, and surface temperature of the hoof as indicators of digital circulation. Lameness examinations were conducted on the same days. There were no consistent treatment differences observed when evaluating measurements of digital circulation. On d 60, horses in the E+ treatment group showed increased hoof sensitivity in the left limb (P = 0.02). These horses tended to have increased hoof sensitivity when both thoracic limbs were averaged (P = 0.06), and they demonstrated increased lameness during longeing (P = 0.08). Data indicated that mares may have increased digital circulation, regardless of treatment, compared with geldings (P ≤ 0.05). Heavier horses also had greater arterial diam., velocity of blood flow, and hoof temperature than lighter BW horses (P ≤ 0.05) on d 30, 60, and 90 at time points that ranged from 90 to 180 min after feeding. Although horses consuming the E+ diet demonstrated increased lameness, especially on d 60, compared with horses consuming the E- diet, the measures of digital circulation did not support the hypothesis that digital circulation was reduced. Because of observed lameness issues, limiting the access of horses to endophyte-infected fescue may be prudent.
Publication Date: 2012-05-14 PubMed ID: 22585825DOI: 10.2527/jas.2011-4371Google Scholar: Lookup
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Summary
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The study examined the effects of horses consuming fescue infected with endophytes, focusing on digital circulation in their lower legs and hoof health. The research revealed increased hoof sensitivity and lameness in horses eating high-endophyte fescue, but no significant changes in digital circulation, prompting recommendations to limit horses’ access to infected fescue.
Experiment Design
- A 90-day study was carried out with 12 American Quarter Horses, split evenly between males and females.
- These horses were divided into two groups: one fed with high-endophyte (E+) fescue, the other with low-endophyte (E-) fescue.
- The E+ diet was formulated to deliver a total of 200 μg/kg of ergovaline, a toxic compound produced by endophytes. In contrast, the E- diet involved endophyte-free fescue seed.
- On days 30-60, the diet was changed; replaced with fescue hay that has high or low endophyte levels, bringing total dietary ergovaline to 280 μg/kg (E+) and 18 μg/kg (E-).
- On days 61-90, the fescue seeds were ground to decrease particle size.
Measurements and Evaluations
- Different metrics were used to evaluate the effect of the diets on the horses. These included Doppler ultrasonography and thermographic imaging, used to measure the diameter of the medial palmar artery (a crucial blood pipeline in the horse’s lower leg), the speed of blood flow, and the surface temperature of the hoof.
- Along with these circulatory measurements, lameness examinations were also conducted on the same days.
- Increased hoof sensitivity was observed in the E+ treatment group on day 60, especially in their left limb. When factoring both legs, a general increase in hoof sensitivity was noted, along with increased lameness during longeing (a form of horse exercise).
- The study also found changes based on gender, with mares (female horses) potentially experiencing more extensive digital circulation regardless of diet compared to geldings (castrated male horses).
- Bodyweight also affected the measurements, with heavier horses showing greater arterial diameter, blood flow velocity, and hoof temperature than lighter horses at various times after feeding.
Study Conclusions
- Despite observing increased hoof sensitivity and lameness in the horses consuming the E+ diet, the research did not find significant changes in digital circulation metrics.
- The results pose questions about the direct link between endophyte-infected fescue consumption and changes in digital circulation in horses.
- However, due to the observed lameness problems, it is suggested to limit horses’ exposure to endophyte-infected fescue as a precautionary measure.
Cite This Article
APA
Douthit TL, Bormann JM, Gradert KC, Lomas LW, DeWitt SF, Kouba JM.
(2012).
The impact of endophyte-infected fescue consumption on digital circulation and lameness in the distal thoracic limb of the horse.
J Anim Sci, 90(9), 3101-3111.
https://doi.org/10.2527/jas.2011-4371 Publication
Researcher Affiliations
- Department of Animal Sciences and Industry, Kansas State University, Manhattan 66506, USA. douthit@ksu.edu
MeSH Terms
- Animals
- Body Weight
- Dose-Response Relationship, Drug
- Endophytes / metabolism
- Female
- Forelimb / blood supply
- Fungi / metabolism
- Hoof and Claw / blood supply
- Horse Diseases / chemically induced
- Horses
- Lameness, Animal / chemically induced
- Male
- Poaceae / microbiology
Citations
This article has been cited 2 times.- Mota-Rojas D, Wang D, Titto CG, Gómez-Prado J, Carvajal-de la Fuente V, Ghezzi M, Boscato-Funes L, Barrios-García H, Torres-Bernal F, Casas-Alvarado A, Martínez-Burnes J. Pathophysiology of Fever and Application of Infrared Thermography (IRT) in the Detection of Sick Domestic Animals: Recent Advances. Animals (Basel) 2021 Aug 5;11(8).
- Reisinger N, Dohnal I, Nagl V, Schaumberger S, Schatzmayr G, Mayer E. Fumonisin B₁ (FB₁) Induces Lamellar Separation and Alters Sphingolipid Metabolism of In Vitro Cultured Hoof Explants. Toxins (Basel) 2016 Mar 24;8(4):89.
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