Defoliating tarbush under multispecies management

TitleDefoliating tarbush under multispecies management
Publication TypeConference Paper
Year of Publication1991
AuthorsAnderson D.M., Gibbens, Robert P., Hulet, Clarence V., Havstad K, Estell R.E.
Conference Name4th US/Mexico Border Conference on Recreation, Parks and Wildlife
Date PublishedMay 1-3, 1991
AbstractTarbush (Flourensiacernua DC.) is a native, perennial, deciduous, warm-season shrub that grows on fertile clay loam soils of the Chihuahuan Desert. Blooming tarbush has been shown to be toxic to ruminants; however, vegetative tarbush can be safely browsed. Under conventional grazing strategies tarbush seldom exceeds 13% of free cattle, sheep and domestic goat diets. Past management practices have encouraged elimination of tarbush by mechanical or chemical means. In an attempt to increase tarbush defoliation, cattle, sheep and Spanish and Angora goats (8:2017:2; 23 AU/ha) were combined to stock 8 0.6 ha paddocks, 4 at a time, over 28 d. Animals were periodically observed to document diets using a modified bite-count technique. Mean annualtarbush leaf, flower and twig production was 385 kg/ha based on 20 plants adjacent to the paddocks that were harvested and separated. Some tarbush received detectable use within the first 48 hours. Defoliation on 120 randomly chosen, individual plants ranged from 5 to 99%. The mean vegetative position of the eight paddocks was 30% grasses, 6% forbs and 11% shrubs other than tarbush. Sheep lost weight (2.3 to 3.0 kg/hd) and body condition (0.8 units), regardless of paddock. Goat body condition did not change overall. Overall, cattle, sheep and Spanish and Angora goat diets were 48, 67, 82 and 84% tarbush, respectively. Short intervals of high-density multispecies stocking reduced tarbush foliage. No health problems were observed in any of the animal species. However, unique plant and animal differences existed which affected tarbush use.