Correlation of Ergovaline and Lolitrem B Levels in Endophyte-Infected Perennial Ryegrass (Lolium Perenne)

Abstract

The varieties of perennial ryegrass ( Lolium perenne) infected with the endophytic fungus Neotiphodium lolii contain several classes of toxic alkaloids, including ergopeptide alkaloids and lolitrem alkaloids. Lolitrem B, a potent tremorgen, is generally considered to be the predominant alkaloid in endophyte-infected perennial ryegrass. Ergovaline, a vasoconstrictor normally associated with endophyte-infected tall fescue ( Festuca arudinacea), is also present in endophyte infected perennial ryegrass. Clinical signs of animals ingesting endophyte-infected perennial ryegrass are consistent with the presence of lolitrem B. However, clinical signs normally associated with ergovaline poisoning are not usually observed in animals ingesting endophyte-infected perennial ryegrass. A survey was conducted to quantitate both lolitrem B and ergovaline in 459 perennial ryegrass straw samples received at the Oregon State University College of Veterinary Medicine. Samples were analyzed for each alkaloid using separate high-performance liquid chromatography analyses. A strong positive correlation between the 2 alkaloids ( r2 = 0.7335) was observed, especially in the samples containing <3,000 ppb (ng/g) lolitrem B. The threshold levels above which clinical signs typically occur are 2,000 ppb lolitrem B and 300–400 ppb ergovaline. All of the samples analyzed contained <425 ppb ergovaline.