Willow (Salix sp.) as a supplement for grazing cattle under drought conditions

This study was undertaken to investigate the effect of willow supplementation of beef cattle grazing dry, sparse summer pastures in the Wairarapa district of New Zealand for 81 days. Three groups each of 15 beef cows were allocated to control, low willow supplementation and high willow supplementation. Liveweight (LW) was measured throughout the experimental period. The chemical composition and nutritive value of the willow and pasture eaten, diameter of willow eaten and willow dry matter (DM) eaten per day were also measured. Post-grazing residual DM was approximately 1700 and 850 kg/ha in the first and second half of the experiment; dead matter content of the feed offered was respectively 0.65 and 0.35 of total DM. Diet selected for willow and drought pasture contained respectively 9.3 and 8.4 MJ ME/kg DM, 18 and 24 g N/kg DM, and 27 and 1 g condensed tannin/kg DM. This defined the pasture as sparse and of low quality, typical of drought conditions. Willow supplementation of cattle grazing dry, sparse summer pasture reduced LW loss (-0.36 to -0.45 kg per day), when compared with a control group grazing similar pasture (-0.64 kg per day). The treatment x time interaction was significant (P < 0.001), explained by willow supplementation being more effective at reducing LW loss as the experiment progressed. There was no significant difference between the levels of willow supplementation (P > 0.10). The diameter of the willow eaten continuously increased over the experimental period (P < 0.01), as did the DM content of the willow offered (P < 0.05), resulting in the amount of willow DM eaten/cow per day continuously increasing throughout the experiment. It was concluded that willow supplementation of beef cattle grazing dry, sparse summer pastures can reduce LW loss under prolonged drought conditions, but that a long feeding period of approximately 55 days is needed before the intake of willow increases to a level that prevents weight loss. Willow can be used as a readily available and low-cost drought supplement. © 2003 Elsevier Science B.V. All rights reserved.