ENDOPHYTE-FREE TALL FESCUE CULTIVARS GRAZED BY SHEEP - FORAGE QUALITYAND SWARD CHARACTERISTICS

Although much work has focused on the performance of endophyte-infecte d (E+), Acremonium coenophialum Morgan-Jones and Gams, tall fescue, Fe stuca arundinacea Schreb.; little information is available comparing p erformance attributes of endophyte-free (E-) cultivars in the northeas tern USA. Five paddocks of four cultivars [(Festorina', 'Johnstone', ' Roa', and 'Kentucky 31' (KY 31)] of E- tall fescue were rotationally s tocked with ewes (Ovis aries) for 2 yr. Tall fescue and weed dry matte r (DM) mass, leaf-to-stem ratio, and tiller density were determined bo th pre-and post-grazing and sward height was measured pre-grazing. For age crude protein (CP), acid-detergent fiber (ADF), neutral-detergent fiber (NDF), and in vitro dry matter disappearance (IVDMD) were determ ined by near infrared reflectance spectroscopy (NIRS). Total dry mass was higher for Festorina and KY 31 than for the other cultivars. Leaf- to-stem ratios were similar among cultivars. Forage height was greates t for Festorina and least for Johnstone. Fescue proportion of herbage biomass nas greater and weed biomass lower for Festorina and KY 31 tha n for Roa and Johnstone. Tall fescue proportion of herbage biomass at the end of the trial nas lowest for Johnstone. Mean tiller densities w ere similar for all cultivars and ranged from 2060 m(-2) in spring to 1260 m(-2) under stockpiling in fall. Pre-grazed herbage CP of 204 g k g(-1) was similar among cultivars. Roa tended to be low and Festorina high in both ADF and NDF, and IVDMD of Johnstone was higher than Festo rina. Across seasons and years, ewe liveweight gain was higher for Joh nstone than for the remaining cultivars, which were similar. Gains for Group 2 (late-weaned) lambs were lower for KY 31 and were similar for the remaining cultivars. In light of this information, cultivar as we ll as endophyte status should be considered in designing experiments o r planning grazing systems with tall fescue.