干旱区生态环境知识资源中心

The significance of encroacher woody plant browse (among other factors) in the composition of the diet of cattle was quantified for July 1996, March 1997 and September 1997. This is important because browse in general is typically ignored in carrying capacity estimates for cattle, while woody encroachers are considered a result of high cattle densities in communal rangelands and therefore undesirable for cattle as feed. There were significant differences in the activities of cattle and woody species utilized between the 3 months. Encroacher moody species (mainly D. cinerea and G. flava) contributed 84.2% in March, 48.3% in July and 21.4% in September towards cattle’s diet out of all the woody species browsed. The woody species recorded high crude protein levels as compared to the grasses. Both the grasses and browse, however, were found to be deficient in phosphorus and the major minerals, except calcium. A temporary protein deficiency for cattle was anticipated in September as the proportion of browse in the cattle’s diet was very low due to the scarcity of browse during this period. There were, however, large quantities of low quality grass cover and cattle tended to graze more, hence no problems were expected with the overall energy supply. The importance of browse (especially woody encroachers) towards cattle’s diet in a communal grazing system, even in a good rainfall year, is emphasized. There is, however, a need for more research to focus upon the dynamics and importance of this much neglected food supply. (C) 1998 Academic Press.