Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/27/2000
Publication Date: N/A
Interpretive Summary: Ergot alkaloids are nitrogen containing compounds produced by an endophyte or fungus living in tall fescue. These toxic alkaloids result in an animal health problem called fescue toxicosis. Knowledge of where and how these compounds are absorbed in animals feeding on tall fescue will aid in understanding which alkaloids are responsible for the health problems and provide incite in developing techniques to overcome the toxicosis. This research suggests that lysergic acid and lysergol produced by tall fescue have greater potential for absorption by the animals than ergopeptine alkaloids. The ergopeptine alkaloids are the most prevalent alkaloids in the tall fescue plant, but the lysergic acid and lysergol appear to be more likely to cause the health problem in animals. This research suggests that blockage of absorption of lysergic acid and lysergol could potentially prevent fescue toxicosis.
Technical Abstract: Ergot alkaloids cause fescue toxicosis when livestock graze endophyte infested (E+) tall fescue. The objective of this study was to examine relative and potential transport of ergoline and ergopeptine alkaloids across isolated gastric tissues in vitro. Sheep gastric tissues were surgically removed and placed in parabiotic chambers. Equimolar concentrations of lysergic acid, lysergol, ergonovine, ergotamine, and ergocryptine were added to a Kreb's Ringer phosphate (KRP) solution on the mucosal side of the tissue and incubating the tissue in near-physiological conditions for 240 min. Samples were taken from the KRP on the serosal side of the chambers at times 0, 30, 60, 120, 180, and 240 min. and analyzed for ergot alkaloids by competitive ELISA. The serosal KRP remaining after incubation was freeze-dried and the alkaloid species quantified by HPLC. The area of ruminal and omasal tissues was measured and the potential transportable alkaloids calculated by multiplying the moles of transported alkaloids per square cm of each tissue type by the surface area of the tissue. Ruminal tissue had greater ergot alkaloid transport potential than omasal tissue (85 vs 60 mmol) because of larger surface area. The ruminal posterior dorsal sac had the greatest potential for alkaloid transport, but the other ruminal tissues were not different from one another. Alkaloid transport was less among reticular tissues than among ruminal tissues. Transport of alkaloids seemed to be an active process with lysergic acid and lysergol having the greatest transport potential. Ergopeptine alkaliods tended to pass omasal tissues in greater quantities than ruminal tissues, but their transport was minimal compared to lysergic acid and lysergol.