Perennial cool-season grasses and legumes form the bases of forage systems in Ohio. These forages produce about two-thirds of their growth by the end of June, with maximum growth during May and June (Blazer et al., 1956). Summer production is generally low with increased growth in the fall. Accumulation of excess spring growth to be grazed later in the summer (Mays and Washko, 1960) is one way to supply adequate summer grazing from cool-season perennials. Three mixtures of perennial cool-season pasture mixtures account for the majority of permanent pastures in Ohio. They are tall fescue mixtures, orchardgrass mixtures, and bluegrass mixtures (Boyles et al., 1996).