Proximate nutrient composition (crude protein,
non-fiber carbohydrates, crude fiber, and ash), fiber fractions (neutral
detergent fiber (NDF), acid detergent fiber (ADF), lignin), and both macro (calcium (Ca), phosphorus (P), magnesium (Mg), potassium (K), sodium (Na), and
sulfur (S)) and trace (copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo),
and zinc (Zn)) mineral profiles were quantified in mixed pasture samples
collected during the wet (n =
8) and dry (n = 15) seasons in north central Uganda. Metabolizable and Net
Energy values for dairy production were estimated based on standard
calculations, and samples were compared seasonally. Crude fat (p = 0.05) and
lignin (p = 0.01) values were lower in the dry compared with the wet season,
linked with reduced plant growth. Crude protein (13.0% of dry matter (DM)), fiber
fractions, and calculated energy content did not vary seasonally in this data
set, and reflected chemical components of a grass-dominated system that
appeared energetically limiting for production livestock. Mineral constituents
varied more dramatically by season, with Ca, Mg, Cu, and Mn lower (all < 0.05) and K higher in the
dry season. Sodium was deficient in these pastures, whereas Ca, P, Mg, S, Cu,
and Zn concentrations may have been only marginally sufficient, particularly to
meet needs for lactation, dependent on season. These limited data suggest that
a high-energy mineral supplement may prove beneficial in meeting nutritional
and production needs of multiple grazing ruminant species in this region,
particularly during dry seasons.