INFLUENCE OF SUPPLEMENTATION METHOD ON FORAGE USE AND GRAZING BEHAVIOR BY BEEF-CATTLE GRAZING BLUESTEM RANGE

Two 25-d trials (late summer and early winter) were conducted to determine the influence of supplementation method on forage use and grazing behavior. Fifteen ruminally and 12 esophageally fistulated steers (316 and 400 kg, respectively) were blocked by weight and assigned randomly to one of three treatments: 1) self-feeding supplement (via Calan gates) with salt as a limiting agent; 2) daily hand-feeding supplement plus salt; and 3) daily hand-feeding supplement without salt. Supplement intake was restricted to .95 kg.steer-1.d-1 with .23 and .40 kg of salt-steer-1.d-1 during summer and winter, respectively. Neither season nor supplementation method affected forage (1.64% of BW) or total (1.89% of BW) OM intake (P > .10). Total OM digestibility was greater (P < .05) in the summer, in salt-supplemented steers, and when steers were self-fed supplement. Digestibility of NDF was greater (P < .05) in the summer than in early winter, but did not differ among treatments (P > .10). Fluid dilution rate was greater (P < .05) for salt-fed and self-fed steers during the summer but similar among treatments (P > .10) during the winter. Total VFA concentrations did not differ among treatments during summer, but were slightly greater (P = .07) in hand-fed steers during the winter. Steers fed supplements containing salt consistently displayed lower (P < .01) acetate:propionate ratios, and self-fed steers had lower (P < .01) acetate:propionate ratios during the summer. Ruminal ammonia concentrations did not differ (P > .10) among treatments and between periods. Grazing time and distance travelled were similar among treatments (P > .10) but both were greater (P < .01) in summer than in winter. In summary, supplementation method occasionally influenced forage use but seemed to exert little influence on the components of grazing behavior measured.