Theme 07: Foraging Strategy
Description
To obtain information on spatially heterogeneous grazing by large herbivores at different time scales, spatial distribution of herbage mass and rate of defoliation was investigated on a bahiagrass (Paspalum notatum Flügge) pasture grazed by cattle during 4 to 5-day grazing periods in May, August and October. Pre-grazing herbage mass (Mpre) showed decreasing mean values and increasing spatial heterogeneity with the progress of grazing in all grazing periods, while the rate of defoliation showed inconsistent changes with season. Spatial distribution of the rate of defoliation was always more heterogeneous than that of Mpre. The correlation coefficient between Mpre and rate of defoliation increased with decreasing mean Mpre on the seasonal basis. The same trends also appeared with the daily progress of grazing in August and October. However, in May when the mean Mpre was less than 40 g DM/2500 cm2, the correlation remained almost constant at significant levels. It was shown that cattle consumed more herbage from locations with greater Mpre as the mean Mpre of the pasture decreased to the critical amount (40 g DM/2500 cm2), but they did not increase their selectivity for higher Mpre locations when the mean Mpre fell below the critical amount.
Included in
The Effect of Herbage Mass of a Pasture on the Spatially Heterogeneous Grazing by Cattle
To obtain information on spatially heterogeneous grazing by large herbivores at different time scales, spatial distribution of herbage mass and rate of defoliation was investigated on a bahiagrass (Paspalum notatum Flügge) pasture grazed by cattle during 4 to 5-day grazing periods in May, August and October. Pre-grazing herbage mass (Mpre) showed decreasing mean values and increasing spatial heterogeneity with the progress of grazing in all grazing periods, while the rate of defoliation showed inconsistent changes with season. Spatial distribution of the rate of defoliation was always more heterogeneous than that of Mpre. The correlation coefficient between Mpre and rate of defoliation increased with decreasing mean Mpre on the seasonal basis. The same trends also appeared with the daily progress of grazing in August and October. However, in May when the mean Mpre was less than 40 g DM/2500 cm2, the correlation remained almost constant at significant levels. It was shown that cattle consumed more herbage from locations with greater Mpre as the mean Mpre of the pasture decreased to the critical amount (40 g DM/2500 cm2), but they did not increase their selectivity for higher Mpre locations when the mean Mpre fell below the critical amount.
