Traditionally managed grazing systems tend to promote reduced forage specie variations compared to unmanaged grazing systems. Work by Wilson et al. (1995) in Pennsylvania suggests that practically all samples of weeds met or exceeded beef and sheep dietary recommendations for magnesium and calcium concentrations, with a lesser proportion of weed species meeting or exceeding phosphorus dietary recommendations. Several weed species had an undesirable high calcium to phosphorus ratio, but the K:(Ca + Mg) ratio indicated that weeds were not generally tetanigenic. Some weed species growing in unmanaged communities can contribute macrominerals, particularly Mg and Ca and microminerals (Cu).