Tall fescue is one of the most widely grown grasses in the United States. Most plants are infected with an endophyte that produces high concentrations of ergot alkaloids, which cause fescue toxicosis in livestock. Of all ergot alkaloids, ergovaline has been determined to be one of the main causes of fescue toxicosis. The economic losses to the US livestock industry are estimated to be approximately $1 billion annually. The objective of this research project was to evaluate the variability in total ergot alkaloid and ergovaline concentrations in the leaf blades, sheaths, and whole tillers from cultivars containing different wild‐type and novel endophytes. This study was conducted in 2012 and 2014 at two sites: Watkinsville, GA and Lexington, KY. Cultivars used in the study were KY31 endophyte infected, KY31 endophyte free, BarOptima Plus E34, Jesup MaxQ, Lacefield MaxQ II, Texoma MaxQ II, and IS-FTF 31-UArk9. There was no difference in total ergot alkaloids or ergovaline concentrations between each location. In 2012, there were no ergovaline-producing tillers in MaxQ or MaxQ II. BarOptima Plus E34 and IS-FTF 31-UArk9 tillers produced ergovaline, but at levels lower than endophyte-infected KY31. Large variability in total ergot alkaloid and ergovaline concentrations were observed across years, within seasons, among cultivars, and within the plant. This study confirmed the extremely high levels of ergovaline and total ergot alkaloids that can be present in endophyte-infected KY31 and indicates the importance of testing fields for total ergot alkaloids and ergovaline content to determine risk to livestock from grazing and hay feeding. While the two current tests, total ergot alkaloid concentration and ergovaline concentration provide different predictions of ergot alkaloid severity, they follow similar trends. For some cultivars (i.e., novel-endophyte cultivars), total ergot alkaloids, may not accurately estimate the effects on livestock, as the proportion of ergovaline is different than that found in endophyte-infected KY31. Producers should test existing fields of KY31 for ergot alkaloid levels and consider replanting with a novel endophyte cultivar if ergovaline levels are high (400–750 µg/kg and 500–800 µg/kg for cattle and sheep consumption, respectively). The recommended practice for replanting with a novel endophyte cultivar is to spray‐kill all existing ergot alkaloid‐producing KY31 tall fescue forage, as well as seedlings that germinate later from the seed bank in the field, and use an interim crop to further suppress endophyte‐infected KY 31. Whereas this practice is highly recommended for replanting tall fescue cultivars with novel endophyte that produce no ergot alkaloids, it is essential to replant with the tall fescue cultivars that produce low levels of ergot alkaloids. The full paper can be downloaded for free here. ~ S Leanne Dillard, S. Ray Smith, and Dennis W. Hancock.
The Alliance for Grassland Renewal is a national organization focused on enhancing the appropriate adoption of novel endophyte tall fescue technology through education, incentives, self-regulation and promotion. For more resources or to learn more about the Alliance for Grassland Renewal, go to www.grasslandrenewal.org
The Alliance for Grassland Renewal 