Grazing of spotted locoweed (Astragalus lentiginosus) by cattle and horses in Arizona.
Abstract: Spotted locoweed (Astragalus lentiginosus var. diphysus) is a toxic, perennial plant that may, if sufficient precipitation occurs, dominate the herbaceous vegetation of pinyon-juniper woodlands on the Colorado Plateau. Six cow/calf pairs and four horses grazed a 20-ha pasture with dense patches of locoweed in eastern Arizona during spring 1998. Locoweed density was 0.7 plants/m2 in the pasture. Locoweed averaged 30.4% NDF and 18.4% CP. Concentrations of the locoweed toxin, swainsonine, fluctuated from 1.25 to 2 mg/g in locoweed. Horses ate more (P < 0.01) bites of locoweed than did cows (15.4 and 5.1% of bites, respectively). Horses generally increased locoweed consumption over time since they ate approximately 5% of bites in the preflower stage compared with 25% of bites in the pod stage. Cattle consumed almost no locoweed (< 1% of bites) until the pod stage, when they increased consumption to 15% of bites. Horses were very avid (approximately 65 to 95% of bites) in selecting the small quantities (approximately 40 to 150 kg/ha) of available green grass, and it appeared that their propensity to eat scarce green forage influenced their locoweed consumption as well. Horses ate relatively little dry grass, even when it was abundant, whereas cattle ate large amounts of dry grass until green grasses became more abundant. Calves began eating locoweed on the same day as their dams and ate approximately 20% of their bites as locoweed. Serum concentrations of swainsonine were higher (P < 0.05) in horses than in cattle (433 vs. 170 ng/mL, respectively). Baseline swainsonine was zero in all animals, but swainsonine was rapidly increased to above 800 ng/mL in serum of horses as they ate locoweed. Horses exhibited depression after eating locoweed for about 2 wk; after 5 wk of exposure, horses became anorectic and behaviorally unstable. Although limited in scope, this study indicates that horses should not be exposed to spotted locoweed.
Publication Date: 2003-09-13 PubMed ID: 12968704DOI: 10.2527/2003.8192285xGoogle Scholar: Lookup
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- Journal Article
Summary
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The study aims to explore the grazing behavior of cattle and horses on a pasture dominated by a toxic plant, Spotted Locoweed, in Arizona, to determine the impact of such consumption and the resulting health implications upon these animals.
Study Overview
- The research was conducted in a 20-hectare pasture abundant in Spotted Locoweed in Eastern Arizona. An analysis of the study indicates the density of Locoweed in the pasture was 0.7 plants per m2.
- Animals involved in the study included six cow/calf pairs and four horses that were allowed to graze freely.
Dietary Analysis
- The researchers noticed that the horses consumed significantly more locoweed than the cows (15.4% of bites compared to 5.1%). Furthermore, the horses’ consumption seemingly increased over time, consuming about 25% of their bites during the mature pod stage of the locoweed.
- Interestingly, cows rarely consumed the locoweed (< 1% of bites) until the pod stage, at which point it comprised 15% of their diet.
- The researchers also found that horses demonstrated a preference for green grass, forgoing the consumption of dry grass even when plentiful.
- However, cattle consumed considerably more dry grass until the availability of green grass increased.
Impact on Calves and Horses
- Calves were observed to start consuming the locoweed same as their mothers and about 20% of their bites were locoweed.
- The horses showed a higher concentration of the locoweed toxin, swainsonine, in their blood compared to the cattle (433 ng/mL vs 170 ng/mL). Swainsonine levels quickly rose in horses’ blood serum upon locoweed consumption, exceeding 800 ng/mL.
- After approximately two weeks of locoweed consumption, horses exhibited depressive behaviors; after about five weeks, horses exhibited anorexic behavior and became behaviorally unstable.
Conclusion
- Though the findings are limited, this study emphasizes the potential hazards of allowing horses to graze on pastures dominated by Spotted Locoweed due to the associated health implications resulting from their consumption choices.
Cite This Article
APA
Pfister JA, Stegelmeier BL, Gardner DR, James LF.
(2003).
Grazing of spotted locoweed (Astragalus lentiginosus) by cattle and horses in Arizona.
J Anim Sci, 81(9), 2285-2293.
https://doi.org/10.2527/2003.8192285x Publication
Researcher Affiliations
- ARS, USDA Poisonous Plant Research Laboratory, Logan, UT 84341, USA. jpfister@cc.usu.edu
MeSH Terms
- Animal Feed / poisoning
- Animal Nutritional Physiological Phenomena
- Animals
- Anorexia / chemically induced
- Anorexia / veterinary
- Arizona
- Astragalus Plant / chemistry
- Astragalus Plant / poisoning
- Behavior, Animal / drug effects
- Cattle
- Cattle Diseases / blood
- Cattle Diseases / etiology
- Enzyme Inhibitors / blood
- Enzyme Inhibitors / poisoning
- Female
- Horse Diseases / blood
- Horse Diseases / etiology
- Horses
- Male
- Plant Poisoning / veterinary
- Plants, Toxic
- Species Specificity
- Swainsonine / administration & dosage
- Swainsonine / blood
- Swainsonine / poisoning
Citations
This article has been cited 2 times.- Cook D, Donzelli BGG, Creamer R, Baucom DL, Gardner DR, Pan J, Moore N, Krasnoff SB, Jaromczyk JW, Schardl CL. Swainsonine Biosynthesis Genes in Diverse Symbiotic and Pathogenic Fungi.. G3 (Bethesda) 2017 Jun 7;7(6):1791-1797.
- Achata Böttger J, Creamer R, Gardner D. Seasonal changes in Undifilum colonization and swainsonine content of locoweeds.. J Chem Ecol 2012 May;38(5):486-95.
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