Evaluation of Tall Fescues for Stocker Cattle in the Gulf Coastal Plain1

New cultivars of nontoxic endophyte-infected (NE) tall fescue must be evaluated under grazing conditions before their commercial release. This research was conducted to compare 2 NE tall fescue cultivars with toxic endophyte-infected Kentucky-31 (KY-31) and an endophyte-free (EF) tall fescue in the Coastal Plain region of southwestern Arkansas. Eleven 0.81-ha pastures were planted to KY-31 (n = 3), EF (cv. Barcel, Barenbrug USA, Tangent, OR; n = 3), or the NE tall fescue cultivars BarOptima, infected with the E-34 endophyte (BarOptima PLUS E-34, Barenbrug USA; n = 3), and Jesup, infected with the AR542 endophyte (MaxQ, Pennington Seed Inc., Madison, GA; n = 2). Pastures were grazed by growing beef calves (n = 33/yr, initial BW = 244 ± 9.5 kg) for 2 yr beginning in January of each year. After 2 grazing seasons, pastures that contained endophyte (KY-31, Jesup AR542, BarOptima PLUS E-34) had greater stand counts than EF (P < 0.01), averaging 83, 78, 70, and 9% stands, respectively. Prolactin concentrations, off-pasture BW, ADG, and BW gain were greater (P ≤ 0.05) for calves grazing NE tall fescue compared with KY-31 in both years. The results of this study indicate that BW gain of calves grazing NE tall fescue in the Coastal Plain of Arkansas was greater than that of calves grazing KY-31, and that persistence of NE was greater than that of EF.