|Johnson, Jennifer -|
Submitted to: American Forage and Grassland Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: April 24, 2010
Publication Date: June 21, 2010
Citation: Johnson, J.M., Aiken, G.E. 2010. Grazing Evaluation of a Novel Endophyte Tall Fescue Developed for the Upper Transition Zone. American Forage and Grassland Conference Proceedings. Interpretive Summary: Tall Fescue is a cool-season perennial bunchgrass that has been utilized in the United States for decades. Kentucky 31 has become the most commonly used and economically important perennial grass in the US by many producers. Tall fescue is a desirable forage due to its wide adaptation, high persistence under different management systems, good forage yield, long-growing season, excellent seed production, and pest resistance. These superior agronomic qualities have been associated with the presence of an endophytic fungus, which has also been linked to negative affects on grazing animals. Novel endophyte strains have been suggested to provide the desirable agronomic qualities without the negative side-affects to grazing animals. A grazing study evaluated the steer performance and forage productivity of a late-maturing novel endophyte experimental population (KYFA9301) developed for the upper transition zone in comparison to Kentucky 31, MaxQ, and endophyte-free tall fescues. Results indicated that steer weight gains were improved, and negative side-effects were not detected in those steers grazing the new experimental population when compared to toxic Kentucky 31 tall fescue. Results indicated KYFA9301 tall fescue provided animal performance and pasture productivity that make it a viable option for alleviating the negative effects caused by grazing Kentucky 31 tall fescue.
Technical Abstract: A wild-type endophyte (Neotyphodium coenophialum) that infests tall fescue [Lolium arundinaceum (Schreb.) Darbysh. = Schedonorous arundinaceum (Schreb.) Dumort.] imparts tolerances to moisture, heat, and grazing stresses, but also produces ergot alkaloids that adversely affect performance and physiology of cattle. Novel endophytes, developed by AgResearch NZ Ltd., can sustain fescue persistence and productivity, but do not produce toxic ergot alkaloids. University of Kentucky Plant Breeder, T. D. Philips Ph.D, developed a tall fescue genotype (KYFA9301) for the upper transition zone. A 2-yr grazing experiment was conducted with steers to evaluate steer performance and physiology, and forage productivity of KYFA9301 infected with AR584 novel endophyte (AR584) compared with KY31 wild-type endophyte (KY31), endophyte-free KYFA9301 (EF9301) and AR542-‘Jesup’ (MaxQ). Fescue-endophyte combinations were assigned to 1.0-ha pastures in a randomized complete block design with three replications. Average daily gains among MaxQ, AR584, and EF9301 were similar and were greater (P < 0.10) than KY31. Rectal and skin temperatures were collected three times each year at approximately days 28, 56, and study completion, along with blood collection for serum prolactin assay. Rectal and skin temperatures among AR584, MaxQ, and EF9301 were similar and were lower (P < 0.10) than KY31. Serum prolactin concentrations were similar among the three nontoxic varieties and higher (P < 0.10) than KY31. Results indicated steer performance and physiological responses for KYFA9301, with and without AR584, were enhanced compared to KY31 and similar to those for MaxQ.