PERFORMANCE OF BEEF REPLACEMENT HEIFERS GRAZING 3 WARM-SEASON PERENNIAL GRASSES

A study was conducted to compare the performance of beef replacement h eifers grazing three warm-season perennial grasses using relatively hi gh levels of N fertilizer. Crossbreed heifers initially 14 mo of age w ith an average weight of 292 kg were blocked according to breed type a nd allotted to pastures of common bermudagrass [Cynodon dactylon (L.) Pers.], 'Alicia' bermudagrass and 'Pensacola' bahiagrass (Paspalum not atum Flugge). All pastures had been established for several years prio r to initiation of the grazing trials on Coastal Plain (Agr Plinthaqui c and Plinthic Paleudults) soils. All pastures received 55 Kg/ha of N as ammonium nitrate starting 3 wiz prior to initial grazing and at 21- d intervals during the grazing period. The ''put and take'' system of grazing management was utilized with stocking rates adjusted ak 3 wk i ntervals based on forage canopy height. Crude protein and neutral dete rgent fiber were highest (P<.0.5) for Alicia bermudagrass, while ligni n was highest (P<.05) for bahiagrass during the grazing season. Forage availability (above ground level) of grazed pastures was 1804, 1398 a nd 1609 kg/ha for common. bermudagrass. Alicia bermudagrass and bahiag rass, respectively. Heifers grazing common bermudagrass had higher (P< .05) daily gains (.36 kg/d) than did heifers grazing either Alicia ber mudagrass (.20 kg/d) or Pensacola bahiagrass (.19 kg/d). Stocking rate s (heifers/ha) were higher (P<0.5) for Alicia pastures compared with c ommon bermudagrass, with bahiagrass pastures being intermediate. The d ata indicate that stocking rate is highest with Alicia bermudagrass, b ut animal performance was greatest using common bermudagrass.