PERFORMANCE OF BEEF STEERS ON SMUTS FINGER GRASS AND NILE GRASS PASTURE IN NORTHERN NATAL .1. EFFECT OF OVERWINTERING LEVEL AND SUMMER STOCKING RATE

In each of three consecutive years (1987/88 to 1989/90), 108 weaner st eers (average live mass = 192.5 and standard deviation = 1.9 kg) were divided into three groups of 36 steers and fed to achieve growth rates of 0, 0.3 and 0.6 kg/steer/day during winter. During the subsequent s ummer, the steers from each wintering level were subdivided into six g roups of six steers each, which grazed either Smuts finger grass (Digi taria eriantha spp eriantha) or Nile grass (Acroceras macrum) pastures , each at one of three stocking rates (6, 8 and 10 steers/ha). Rotatio nal grazing was applied. On average, steers subjected to wintering lev els of 0, 0.3 and 0.6 kg/day subsequently gained 47.1 +/- 1.7, 38.2 +/ - 2.1 and 34.9 +/- 2.2 kg/steer on Smuts finger grass and 63.5 +/- 2.2 , 55.7 +/- 2.3 and 42.8 +/- 2.7 kg/steer on Nile grass pasture over a 90-day grazing period. Steers subjected to stocking rates of 6, 8 and 10 steers/ha gained 45.1 +/- 2.0, 39.2 +/- 1.8 and 35.8 +/- 2.4 kg/ste er on Smuts finger grass and 61.8 +/- 2.1, 58.7 +/- 2.2 and 41.6 +/- 2 .8 kg/steer on Nile grass. Prediction equations for summer live mass g ain and final live mass were calculated. For all treatments, steers ha d better live mass gains when grazing Nile grass than when grazing Smu ts finger grass [54.0 +/- 1.5 and 40.0 +/- 1.2 kg (P less than or equa l to 0.01), respectively]. It was not clear whether the higher summer growth-rate on both pastures in animals wintered at maintenance was du e to compensatory growth or to relatively more grass/kg live weight be ing available to the lighter animals.