Tiller Defoliation in a Moderate and Heavy Grazing Regime

Abstract

An investigation defining the intensity and frequency of tiller defoliation in brownseed paspalum (Paspalum plicatulum), a native perennial, bunchgrass, was conducted with yearling steers in a moderate and heavy grazing regime. Tillers were marked with alternately colored loops of plastic-coated wire so that an individual tiller could be located on successive sampling dates. Tiller height was reduced 50% within 7 days in the heavy grazing regime. The percentage of leaves defoliated per tiller was 63, 78 and 82 following 4, 7 and 11 days of grazing, respectively. Tillers in the heavy grazing regime were uniformly regrazed at approximately 3 to 4 day intervals. A significant reduction in tiller height did not occur in the moderate grazing regime until after 18 days of grazing and tiller height was reduced only 46% at the end of the 33-day grazing trial. The percentage of leaves defoliated per tiller was 5, 9 and 26 following 11, 21, and 33 days of grazing, respectively. By the end of the moderate grazing trial 82% of the tillers were grazed at least once, 31% at least twice and 10% at least 3 times. The nonuniform frequency of tiller defoliation and wide range of tiller heights at the end of the moderate grazing trial resulted in an inefficient harvest of available tillers.