Studies on the Magnesium Status of Grassland Herbage and Its Possible Significance in Animal Health

Various forms of magnesium compounds were applied to grassland managed under modern intensive conditions and the effects on yield and composition of the herbage were measured. Magnesium limestone increased both yield and magnesium content. Commercial magnesite (MgO) increased the magnesium content rapidly and also gave a small increase in yield. An annual dressing of magnesium sulphate had little effect on magnesium content and tended to depress yield after two years. A marked seasonal effect exists in pasture magnesium content. Increasing the magnesium content had little effect on its distribution within the plant, but it tended to depress calcium and potash. The results are discussed with special reference to recent research on the magnesium metabolism in dairy cattle.