Seasonal diet preference of cattle, sheep and goats grazing on the communal grazing rangeland in the Central District of Botswana

摘要

Diet composition, forage preference and diet overlap among of goats, sheep and cattle grazing on communal rangeland in the Central District of Botswana were evaluated to determine the potential for forage competition to provide better ideas for managing these rangelands. Diets and forage preference were determined through microhistological faecal analysis. Animal faeces and reference plant material of the study area were collected, ground to fine particles and prepared into slides of which histological features of each animal species were studied under the microscope. Features on the faecal sample slides were matched with those in the reference plant material. Estimates of forage biomass and quality were estimated along transects and species composition was determined using a wheel-point apparatus. Season was a major factor affecting herbage biomass and quality. Forage quality decreased from wet to dry season with greater decreases in grass than browse. The content of nitrogen was higher in browse than in herbage in both seasons, and the seasonal decline in browse was less than in herbage. Cattle and sheep diets constituted mostly grasses, but cattle do browse as well during the dry periods. Goats selectively concentrate on browse all the year-long and were more diverse in their diet composition than either cattle or sheep, giving the former better chances of standing harsh conditions. Preferred plant species were not the necessarily the most common on the range. Therefore, monitoring productivity and use of key forage species, particularly of grasses, should complement management objectives.Diets overlaps were generally high during dry seasons, reflected seasonal influence as animals shift diets focus, when the potentials of forage selections are restricted to limited species diversity and availability. The results suggest potential for forage competition between cattle and sheep is highest during dry seasons for grasses.