TOBOSA TILLER DEFOLIATION PATTERNS UNDER ROTATIONAL AND CONTINUOUS STOCKING

Continuous low animal density grazing of tobosa [Hilaria mutica (Buckl .) Benth.] in the northern Chihuahuan desert results in nonuniform for age utilization, Stocking smaller tobosa rangeland paddocks with high numbers of cattle for short periods of time may facilitate more unifor m forage utilization, Two grazing periods in each of 2 consecutive yea rs were monitored to investigate the frequency with which tobosa tille rs were defoliated and the intensity of defoliation (change in height) in relation to grazing pressure under high-density seasonal rotationa l and low-density seasonal continuous grazing. Approximately 40% of ti ller height, including leaves, was removed at each defoliation in the rotational treatment, while intensity of defoliation per grazing event remained consistent. In the continuous treatment, amount of tiller re moved varied widely and was not consistent among the 4 periods. Percen tage of tillers defoliated in the rotational treatment was always grea ter than 75%, and always less than 30% in the continuous treatment, Th e probability that a tiller would be grazed at least once in the rotat ional treatment was more than twice as great as in the continuous trea tment. However, within the rotational treatment, the probability of mu ltiple grazing events (greater than or equal to 2) on an individual ti ller was less than the probability of a tiller being grazed just once, In general, high-density rotation grazing promoted more uniform forag e utilization of tobosa than low-density continuous grazing.