GRAZING INITIATION DATE AND STOCKING RATE EFFECTS ON PASTURE PRODUCTIVITY

Date of grazing initiation in spring and stocking rate have large effe cts on both animal and pasture productivity. A grazing experiment with yearling steers (Bos taurus L.; average 320 kg) was conducted in the growing season of three years to compare two dates of grazing initiati on (differing by 2 wk) at three stocking rates (3, 4, and 5 steers ha- 1) on set-stocked naturalized pasture in the Appalachian USA. Pasture botanical composition, herbage mass and accumulation, and animal livew eight changes were measured. Early grazing initiation increased percen tage grass in the pasture compared with late initiation. Crude protein concentration was higher, and acid- and neutral-detergent fiber were lower in pastures on which grazing was initiated earlier. Herbage mass was >33% more at the later grazing initiation date compared with the early initiation date. Earlier grazing initiation did not affect pastu re dry matter accumulation or average daily gain but animal gain per h ectare was almost 20% higher with earlier grazing. Stocking rate the p revious year had no effect on botanical composition or herbage mass at initiation of grazing. Average daily gain was highest at 4 steers ha- 1 (0.81 kg) and lowest at 5 steers ha-1 (0.62 kg). Animal production p er hectare was almost 50% greater at 4 steers ha-1 (358 kg) than at 3 steers ha-1 (246 kg). We conclude that naturalized pasture in Appalach ia can be grazed early without detrimental effects.