Cutting management of willows (Salix spp) and leguminous shrubs for forage during summer

An experiment was conducted to determine the potential value of shrubs for providing fodder for ruminants during periods of feed insufficiency. The work was undertaken at a moist and a dry site in the lower North Island of New Zealand in 1992/93 with four shrub species: Chamaecytisus palmensis (tagasaste); Dorycnium rectum (erect dorycnium); Salix kinuyanagi (kinuyanagi willow); and Salix matsudana x alba (hybrid willow). Five cutting regimes were adopted which varied in cutting frequency and height, with. the latter being either a low (L) or high (H) cutting height. There was a single low cut (L) in April at the end of the growing season, 2 cuts (LL and HL treatments) in February and April, and 3 cuts (LLL and HHL treatments) in December, February, and April. Three cuts during the season were investigated only at the moist site. Whole plant yields over the 1992/93 growing season were highest from a single cut in April. However, 2- and 3-cut treatments sometimes gave yields as high as those from a single cut (P < 0.05), particularly when the first cut was high. C. palmensis (7.7-16.7 t dry matter (DM)/ha) and D. rectum (0.1-4.8 t DM/ha) were the highest- and lowest-yielding species, respectively, at each site, with Salix spp. (1.0-9.9 t DM/ha) palmensis had the highest quality forage with in vitro organic matter digestibility (OMD) of 77-85% and total nitrogen (N) content of 26-40 g N/ kg DM, and it was unique among the species in having consistent high quality throughout the season at both sites. The Salix spp. and D. rectum had an average total N content of 25 g N/kg DM. S. kinuyanagi (46%) and D. rectum (53%) had lower OMD than S. matsudana x alba (71%), perhaps because of the formers' relatively high lignin contents (67-95 g/kg DM). It was concluded that C. palmensis particularly, and Salix matsudana x alba, could be valuable for supplying supplementary forage during the summer in dry areas.