Agronomic Performance and Lamb Health among Several Tall Fescue Novel Endophyte Combinations in the South-Central USA

Deployment of novel endophytes [Neotyphodium (Morgan-Jones & Gams) Glenn, Bacon & Hanlin] may expand the use of tall fescue [Lolium arundinaceum (Schreb.) S.J. Darbyshire] in the south-central United States. Our objectives were to compare agronomic performance of, and health of lambs (Ovis aries) grazing, several tall fescue-novel endophyte combinations in the south-central United States Two tall fescue populations (97TF1 and PDF) were inoculated with four novel endophytes (AR514, AR524, AR542, and AR584). At most locations, persistence of the eight combinations under grazing by beef cattle (Bos taurus) was similar to Jesup MaxQ. However, the combination PDF AR584 had greater persistence than Jesup MaxQ at Booneville, AR (24 vs. 14% stands, respectively) and Burneyville, OK (31 vs. 8% stands, respectively). Forage yields of the eight combinations were comparable to Jesup MaxQ, with PDF AR584 having greater yields on occasion. Lambs grazing PDF AR584, 97TF1 AR584, PDF AR542, PDF AR524, and Jesup MaxQ gained an average of >139 g more than twice the 68 g d(-1) gained by animals grazing endophyte-infected Kentucky-31. Prolactin and urinary alkaloid data indicated no detrimental health effects for animals grazing the novel endophyte combinations. Several tall fescue-novel endophyte combinations, and in particular PDF AR584, appear to be suited for the south-central United States, based on competitive agronomic performance and health of grazing lambs.