The mineral scoring technique and evaluation of indigenous browse species as natural mineral phytocentres for goats in African rangelands.

The utilization and evaluation of indigenous browse species as natural mineral phytocentres for goats was examined by the combined use of mineral concentrations, mineral scores, browse accessibility and abundance in the Ankole rangeland, Uganda. The species Grewia bicolor and Carissa edulis with > 140% mineral scores and > 70% accessibility were the most valuable mineral phytocentres and were the victims of overgrazing. Acacia albida and Acacia abyssinica with > 130% mineral scores but < 30% browse accessibility were valuable for the cut-and-carry feeding system. Species mineral scores at average and maximum dietary recommendations were < 60%, highlighting the mineral insufficiency of range browse for high-performance goats. Mineral supply potential was highest (35.0%) in the genus Acacia and lowest (5.3%) in Dichrostachsys. Browse accessibility was < 35%, in 69.2% of species. Acacia hockii was the most abundant species (24.5%) but had the lowest mineral score (17.7%). Browse species (90-100%) were deficient in Fe, Mn, Cu and Zn. The combined use of mineral concentrations and mineral scoring technique was superior to the use of mineral concentrations alone in defining mineral adequacy, deficiency and supply potential, making the mineral scoring technique a valuable tool in browse management.