Gb. Douglas et al., CUTTING MANAGEMENT OF WILLOWS (SALIX SPP) AND LEGUMINOUS SHRUBS FOR FORAGE DURING SUMMER, New Zealand Journal of Agricultural Research, 39(2), 1996, pp. 175-184
An experiment was conducted to determine the potential value of shrubs
for providing fodder for ruminants during periods of feed insufficien
cy. The work was undertaken at a moist and a dry site in the lower Nor
th Island of New Zealand in 1992/93 with four shrub species: Chamaecyt
isus palmensis (tagasaste); Dorycnium rectum (erect dorycnium); Salix
kinuyanagi (kinuyanagi willow); and Salix matsudana x alba (hybrid wil
low). Five cutting regimes were adopted which varied in cutting freque
ncy and height, with. the latter being either a low (L) or high (H) cu
tting height. There was a single low cut (L) in April at the end of th
e 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 gav
e yields as high as those from a single cut (P < 0.05), particularly w
hen the first cut was high. C. palmensis (7.7-16.7 t dry matter (DM)/h
a) and D. rectum (0.1-4.8 t DM/ha) were the highest- and lowest-yieldi
ng 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 mat
ter 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 consiste
nt high quality throughout the season at both sites. The Salix spp. an
d D. rectum had an average total N content of 25 g N/kg DM. S. kinuyan
agi (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.