|JOHNSON, JENNIFER - University Of Kentucky|
|PHILLIPS, TIM - University Of Kentucky|
|BARRETT, MIKE - University Of Kentucky|
Submitted to: Agronomy Society of America, Crop Science Society of America, Soil Science Society of America Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 4/30/2009
Publication Date: 11/1/2009
Citation: Johnson, J., Aiken, G.E., Phillips, T., Barrett, M. 2009. Grazing Evaluation of a Novel Endophyte Tall Fescue Developed for the Upper Transition Zone. Agronomy Society of America, Crop Science Society of America, Soil Science Society of America Meeting.
Technical Abstract: A wild-type endophyte (Neotyphodium coenophialum)that infests tall fescue (Lolium arundinaceum) imparts tolerances to moisture, heat, and grazing stresses, but also produces ergot alkaloids that adversely affect performance and physiology of cattle. Novel endophytes can sustain fescue persistence and productivity, but do not produce toxic ergot alkaloids. A 2-yr grazing experiment is being conducted with yearling steers to evaluate steer performance/physiology and forage quality/productivity for a novel endophyte tall fescue, AR584-KYFA9301 (NE9301; not commercially released), in comparison to AR542-‘Jesup’ (MaxQ), endophyte-free KYFA9301 (EF9301), and wild-type ‘Kentucky 31 (KY31) tall fescues. Entries were assigned to 1.0-ha pastures in a completely randomized design with three replications. Pastures were planted in September of 2006. Grazing with variable stocking (4 testers) was initiated in 2008 on May and terminated on July. Shrunk bodyweights were taken at the beginning (mean bodyweight = 304 ± 34 kg) and end of the grazing season. Rectal and skin temperatures were recorded on days 28, 56, and 77. Average daily gains among MaxQ (0.87 kg d-1), NE9301 (0.74 kg d-1), and EF9301 (0.74 kg d-1) were similar (P > 0.10), and these were greater (P < 0.05) than KY31 (0.57 kg d-1). Rectal and skin temperatures among NE9301, EF 9301, and MaxQ were similar (P > 0.10), and these were less (P < 0.05) than KY31. Carrying capacities were similar (P > 0.10) among entries (431 ± 19 steer d ha-1). Results in the first year indicated steer performance and body temperature responses for NE9301 and EF9301 were similar to those for MaxQ.