ABSTRACT
Summary Mefluidide treatment of Kentucky 31 tall fescue (Festuca arundinacea Schreb.) in the spring will inhibit seed-head formation, maintain the forage in an immature and vegetative stage, and increase forage N and soluble-sugar content and in-vivo nutrient utilization in the ovine. Productivity of animals grazing mefluidide-treated tall fescue, however, has not been determined. The objective of this study was to evaluate agronomic characteristics of forage and productivity of yearling beef steers and heifers grazing mefluidide-treated (T) and nontreated control (C) pastures of Kentucky 31 tall fescue. Experimental pastures of Kentucky 31 tall fescue (4 replications at location I and one replication at location II) were used to determine the effect of a spring application of 273.8 g mefluidide/ha on forage N, forage soluble sugars, and animal gain at 28-day intervals in two 140-day grazing seasons. Mefluidide-treated forage had higher (P < 0.05) N content than the control on days 56, 84, and 112 of the grazing season in both years. Forage soluble-sugar content of treated fescue was greater (P < 0.05) than that of the control on days 28, 56, and 112 of the first year's grazing season and greater (P < 0.05) on day 28 of the second year. Animal gain from grazing treated forage was increased 9%, 22%, 380%, and 21% over control for 0 to 28-, 28 to 56-, 56 to 84-, and 84 to 112-day periods, respectively. Combining gain data and analyses for forage treatment, year, location, and 2- and 3-way interactions produced a positive (P < 0.01) effect for mefluidide treatment. Mefluidide treatment of Kentucky 31 tall fescue inhibited seed-head formation, increased forage N and forage soluble-sugar content, and produced a forage that was more efficiently utilized by grazing animals than nontreated forage. This treatment resulted in a 27% increase in animal productivity/ha.
