Steer and Plant Responses to Chemical Suppression of Seedhead Emergence in Toxic Endophyte-Infected Tall Fescue

Chaparral herbicide has been shown to suppress seedhead emergence in tall fescue [Lolium arundinaceum (Schreb.) Darbysh] and potentially mitigate the effects of fescue toxicosis. A two-year grazing experiment evaluated steers grazed on endophyte-infected fescue–Kentucky bluegrass (Poa pratensis L.) pastures either treated or untreated with Chaparral herbicide to determine if seedhead suppression alleviates fescue toxicosis and increases average daily gain (ADG). Treatments were assigned to six, 3.0-ha fescue-bluegrass pastures in a randomized complete block design with three replications. Pastures were grazed with 48 steers (2.7 steers ha−1) from 9 Apr. to 1 July 2009 and 6 Apr. to 7 July 2010. Reproductive tiller densities in treated pastures were low in both years (