Two common use grazing trials were conducted during two summer grazing seasons (1978-1979) on a typical shrubby grassland site on the Kolob Terrace, about 20 miles (32 km) southeas t of Cedar City, Utah, at an elevation of about 8500 feet (2600 m). Two animal units of ewes with lambs, or cows with calves, or both were stocked in each of six, one acre (0.39 ha) pastures. A five to one substitution ratio provided two single-species and one mixed (five ewes with lambs and one cow with calf) livestock treatments replicated twice . The pastures were grazed for nine days during which time two major experiments were performed.