Nutritional Characteristics of High Yielding Exotic Grasses for Seeding Cleared South Texas Brushland

Abstract

Three exotic grasses potentially useful converting south Texas brush rangeland to permanent pasture were evaluated in 1976 and 1977. Yearling cattle required 16.6, 23.1, and 34.8 kg of forage per kg of gain for coastcross-1 bermudagrass, kleingrass-75, and Bell rhodesgrass, respectively. Cattle gained 0.68, 0.56, and 0.33 kg/head daily grazing these species. They ate (forage disappearing) about 12 kg/head daily regardiess of species, so daily gains directly reflected differences in quality among the forages. Our data suggest that the quality measure most nearly deficient was the factor most limiting animal performance, e.g., correlation between average daily gain and P content was r = 0.89 for cattle grazing Bell rhodesgrass. Its P content varied from 0.16 to 0.06% from spring to fall compared to 0.24 to 0.15% from spring to fall for the other two forages. Overall, 24-hr IVDMD (fermentation only) best correlated with animal daily gain. Generally, Bell rhodegrass had lowest, coastcross-1 bermudagrass highest, and kleingrass-75 intermediate quality values, particularly for digestibility, crude protein, and digestible energy. Dry matter yields were 9.6, 11.6, and 11.8 thousand kg/ha for coastcross-1 bermudagrass, kleingrass-75, and Bell rhodesgrass in 1976.