Effect of sward surface height on herbage intake and performance of finishing beef cattle

This study examined the effects of contrasting sward surface height (SSH) o n the herbage intake, ingestive behaviour, and performance of steers grazin g perennial ryegrass (Lolium perenne)/white clover (Trifolium repens) pastu res in New Zealand during summer, and the influence of this initial treatme nt contrast on subsequent cattle performance under common grazing condition s during early autumn. Twenty-four Angus-cross steers, 26 months old and wi th an initial liveweight of 522 +/- 7.6 kg, were continuously stocked on sw ards maintained at SSH of 5 and 10 cm (L versus H) from 18 November 1996, S ix steers from each treatment were slaughtered on 4 March and the remaining animals were grazed for another 5 weeks on common pastures until the final slaughter on 8 April 1997. Herbage intake (estimated by the n-alkane technique) and liveweight gain ov er the SSH contrast period, and carcass weight at first slaughter, were hig her for steers grazed at 10 cm than for those grazed at 5 cm (7.5 +/- 0.21 versus 5.0 +/- 0.18 and 7.8 +/- 0.38 versus 5.0 +/- 0.33 kg DM d(-1) from t wo intake estimates, P < 0.05 for each comparison; 1.10 +/- 0.23 versus 0.3 2 +/- 0.21 kg d(-1), P < 0.01; and 332 +/- 10.6 versus 287 +/- 7.5 kg, P < 0.05, respectively). SSH did not affect carcass or meat quality characteris tics. Liveweight and carcass weight gain per hectare were 71% and 43% great er (318 versus 186 kg and 166 versus 116 kg over 105 days) for steers grazi ng at 10 cm despite the lower stocking rate (2.86 versus 5.80 steers hat) m aintained by the tall swards. Significant differences in carcass weight wer e still evident at the end of the compensatory period between the steer gro ups originally on treatments H and L (335 +/- 9.4 versus 297 +/- 9.4 kg, P < 0.05). These results suggest that maintaining a sward height of 10 cm offers advan tages in terms of individual animal output and output per hectare compared with grazing at 5 cm, and that compensatory growth does not seem to be an i mportant phenomenon in heavy lover 500 kg liveweight) finishing steers.