Animal health problems caused by silicon and other mineral imbalances

Plant growth depends upon C, H, O, and at least 13 mineral elements. Six of these (N, K, Ca, Mg, P, and S) macro-elements normally occur in plants at concentrations greater than 1,000 mg kg(-1) level. The remaining micro-elem ents (B, Cl, Cu, Fe, Mn, Mo, and Zn) normally occur in plants at concentrat ions less than 50 mg kg(-1). Trace amounts of other elements (e.g., Co, Na, Ni, and Si) may be beneficial for plants. Silicon concentrations may range upwards to 50,000 mg kg(-1) in some forage grasses. Mineral elements requi red by animals include the macro-elements Ca, CI, K, Mg, N, Na, P, and S; t he trace or micro-elements Co, Cu, Fe, I, Mn, Mo, Se, and Zn; and the ultra -trace elements Cr, Li, and Ni. When concentrations of these elements in fo rages get Lout of whack' their bioavailability to animals may be jeopardize d. Interactions of K x Mg x Ca, Ca x P, Se x S, and Cu x: Mo x S are briefl y mentioned her e because more detail will be found in the literature. Limi ted published information is available on Si, so we have provided more deta il. Silicon provides physical support to plants and may reduce susceptibili ty to pests, However, Si may have negative effects on digestibility and con tribute to urinary calculi in animals.