Mineral, protein, and fiber content are important components of forage quality in perennial grasses. The ratio of K to Ca and Mg (KRAT) is a useful predictor of grass tetany, which is metabolic aliment occuring when animals graze rapidly growing cool-season grasses. We measured Al, B, Ca, Cl, Cu, Fe, K, Mg, Mn, Na, P, S, Si, ,Zn, KRAT, protein (N), and fiber content in forage samples from clonally replicated field trials (2003 and 2004) of the Leymus triticoides x (L. triticoides x L. cinereus) 164-sib TTC1 and 170-sib TTC2 mapping populations. High-density molecular genetic linkage maps were used to identify and characterize QTLs controlling these traits.