Grazing and cutting management of alamo switchgrass in Alabama

Abstract

Switchgrass has potential for beef cattle enterprises in Alabama, but few grazing studies have been conducted with it `Alamo’ switchgrass is the highest-yielding variety of Alabama, but it has not been evaluated under grazing. Therefore, the objectives of this research were to determine the effect of: 1) defoliation intensity on morphology and biomass of Alamo; 2) timing of the first harvest on yield and quality of Alamo; and 3) stocking rate and stocking method on steer performance, pasture growth and forage quality. A greenhouse study evaluated effects of 5-, 15-, and 25- cm stubble heights on biomass production and morphology. Results indicated that total yield and growth regrowth yield, stubble and below- ground biomass, leaf area, leaf –to-stem ratio, leaf number/tiller and stem length tended to increase (P<0.05) as stubble height increased. A plot study (E.V. Smith Research Center) compared cutting intervals (3, 6 and 9 weeks) withearly or late initial cuts in 1995 and 1996. Overall, the early-start and longer cutting intervals produced the highest seasonal dry matter (DM) yield, neutral detergent fiber (NDF) and acid detergent fiber (ADF) concentrations, but lower crude protein (CP) concentration. In a grazing study at the wiregrass substation in 1995 and 1996, paddocks were stocked at 5.71, 7.61 and 9.51 sterrs haˉ1 and grazed continuously (CS) or rotationally (RS). More forage present decreased as SR increased, except under RS in the first season where there was no change. Forage quality tended to be higher under CS than under RS, and at higher SR. Average daily gains (ADG) in the first season were similar for both methods and decreased slightly (P<0.05) between methods and decreased as SR increased as day 56 of grazing.