Date of Award

12-2017

Degree Type

Thesis

Degree Name

Master of Science

Major

Animal Science

Major Professor

Justin D. Rhinehart

Committee Members

Jason K. Smith, Patrick D. Keyser, Gary E. Bates

Abstract

Drought conditions have had detrimental effects on beef cattle production in the southeastern states where forages are the primary source of feed for livestock. Many southeastern states lie within the fescue-belt, where tall fescue is the predominant livestock forage. Tall fescue is a cool-season (CS) grass that thrives in the cooler temperatures of spring and fall, becoming semi-dormant during peak summer temperatures and again in winter. Conversely, warm-season (WS) forage species increase in production during the summer months and exhibit drought tolerant qualities, making them a viable summer forage option to complement tall fescue for beef cattle producers. The primary objective of this study is to evaluate various WS forage options and how they can help producers cope with drought. To accomplish this objective, a side-by-side comparison of five WS grasses were evaluated for production, nutrient density, and animal performance. The five WS grasses analyzed were: switchgrass (SW), eastern gamagrass (EG), big bluestem and Indiangrass mixture (BBI), bermudagrass (BG), and crabgrass (CG). This study was conducted over three years (2014, 2015, and 2016) at two locations: Ames Plantation Research and Education Center (APREC), and Highland Rim Research and Education Center (HRREC). To analyze animal performance, four heifers were placed on 1.2-ha paddocks with three replications per treatment. All test heifers were fed an equilibrium diet at the beginning and end of the grazing trial to help decrease variation in gut fill. The put-and-take method was used with additional heifers to help maintain targeted forage heights. Data was analyzed with SAS 9.4 (SAS Institute, Cary, N.C.) using the mixed model analysis of variance. When comparing the 5 species of forage, average daily gains (kg/day) were 0.62, 0.41, 0.44, 0.42, and 0.51, BBI, BG, CG, EG, and SW; respectively. Grazing days (days/ha) were 412, 459, 455, 664, and 617, BBI, BG, CG, EG, and SW; respectively. Total gain per ha (kg/ha) were 259, 186, 200, 276, and 315, BBI, BG, CG, EG, and SW; respectively. Grazing WS grasses during the summer months can be a complementary tool to producers grazing cattle on CS grasses.

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