Seasonal variation in macro and micro mineral contents of browse plants consumed by ruminants in Namibia

This study evaluated the seasonal variation of macro and micro minerals contents of woody plant leaves and their interaction: species x season. The woody plants species investigated from Daurês, Gibeon, Guinas, Kongola, Omatako and Tsandi constituencies were Senegalia mellifera, Vachellia karroo, Vachellia hereroensis, Dichrostachys cinerea, Grewia bicolor, Combretum apiculatum, Combretum collinum, Philenoptera nelsii, Terminalia prunioides, Terminalia sericea, Colophospermum mopane, Baphiam massaiensis, Bauhinia petersiana, Catophractes alexandri, Rhigozum trichotomum and Ziziphus mucronata. Leaves of woody species were collected in the wet, early-dry and late dry seasons. Minerals contents varied between species, seasons and their interactions. Species × season interactions were observed in calcium (Ca), potassium (K), magnesium (Mg) and sulphur (S). Calcium, P, Mg, K and S were affected by season (p < 0.0001). Sodium, Ca, K and S levels differed by species. Micro-mineral contents were significantly affected by species, season and their interactions (p < 0.0001) except for copper which was not influenced by season. Most woody plants meet the minimum requirement of most minerals for ruminants; however, supplementation is vital, especially during the dry season. Metabolic trials are required to understand mineral metabolism and bioavailability, and ultimately their impact on animal performance.