Abstract | The deciduous shrub tarbush (Flourensiacernua DC.) grows on fertile clay loam soils of 5 to 6 x 106 ha of North America's Chihuahuan Desert. Blooming tarbush is toxic to ruminants, whereas vegetative tarbush can be safely browsed. Under conventional management strategies tarbush seldom exceeds 15% of free-ranging animal diets. In an attempt to defoliate tarbush cattle, sheep, Spanish goats and Angora goats (8:20:17:2; 23 AU/ha) were used to stock eight 0.6 ha paddocks, four at a time, for 8 to 9 days during vegetative growth between August and September 1989. Mean tarbush canopy cover, estimated using line-point transects, was 17% and 11% before and after stocking, respectively. Daily tarbush defoliation was monitored on 120 plants randomly chosen among the eight paddocks. In addition, 20 tarbush plants, adjacent to the paddocks, were hand-harvested and -separated. Mean annual tarbush leaf, flower and twig production was 385 kg/ha. Individual tarbush plant defoliation ranged from 5 to 99%. Cattle refused to browse only tarbush and were the first animal species removed due to a lack of other available forage. Sheep consistently lost liveweight (2.3 to 3.0 kg/hd) and body condition (0.8 unit) regardless of paddock. Goat body condition did not change overall. In four of the paddocks, Spanish goats gained 0.5 kg/ha while Angoras lost 1.4 kg/hd. Goat liveweight in the remaining four paddocks did not change (P > 0.05). Overall, 48, 67, 82 and 84% of cattle, sheep, Spanish goat and Angora goat diets were tarbush, respectively. Short intervals of high-density multispecies stocking reduced tarbush foliage. However, unique plant and animal differences existed which affected tarbush use. |