New Zealand Journal of Agricultural Research abstracts
Fortification of silage and hay crops with trace elements
L. C. Smith
AgResearch
Woodlands Research Station
RD1
Invercargill, New Zealand
chris.smith@agresearch.co.nz
J. D. Morton*
AgResearch
Invermay Agricultural Centre
Private Bag 50 034
Mosgiel
R. D. Longhurst
M. B. O’Connor
AgResearch
Ruakura Agricultural Centre
Private Bag 3123
Hamilton, New Zealand
W. D. Catto
Ballance Agri-Nutrients
Hewletts Road
Private Bag 12 503
Mount Maunganui, New Zealand
*Present address: Ballance Agri-Nutrients, P.O. Box 63, Rolleston, Canterbury, New Zealand.
Abstract Feeding out conserved hay or silage to
animals over winter or in early spring is an integral part of New
Zealand pastoral farming. However, the mineral content of conserved
feed is usually below that of the original pasture, and is fed to stock
at a time when their mineral requirements are high. During these
periods, iodine and copper concentrations in pasture are marginal or
deficient, exacerbating the problem. Three trials were laid down, two
in Southland and one in the Waikato, looking at the uptake of copper
(Cu), cobalt (Co), selenium (Se), and iodine (I) when applied in liquid
form at various times between the shutting-up stage and harvesting of
conserved silage and hay paddocks. Application times for the Southland
trials were 4 weeks prior to cutting, 2 weeks prior to cutting, the
same day as cutting and onto the windrow after cutting. Minerals
applied and rates of application were Cu: 0, 0.5, 1 and 3 kg
copper sulphate ha–1, Se: 10 g Se ha–1 as sodium selenate, I: 200 g potassium iodate ha–1, and Co: 60 g cobalt sulphate ha–1. For the Waikato trials two rates of copper sulphate (1 and 2 kg ha–1)
along with one rate of Co, Se and I were spray applied to silage and
hay crops 4 and 7 weeks before harvesting respectively. The application
of 3 kg CuSO4 ha–1 as a spray to pastures 4 weeks prior to them being harvested increased the Cu status of the silage from 9 to 18 mg kg–1 and from 8 to 15 mg kg–1, and of the hay from 12 to 49 mg kg–1 and from 7 to 13 mg kg–1 at the two Southland trials respectively. However, only the increase from 12 to 49 mg kg–1 was statistically significant (P < 0.001). In the Waikato the application of 2 kg CuSO4 ha–1 lifted the Cu concentration from 7 to 11 ppm, and from 6 to 9 ppm for the silage and hay respectively (P < 0.01). In Southland the application of 0.5 kg CuSO4 ha–1
directly onto the windrow following cutting increased Cu concentrations
from 8 to 31 ppm for the silage and from 12 to 63 ppm and 7 to 24 ppm
for the hay (P < 0.001). It is recommended that
to increase the Cu status of silage and hay sufficient to supply the
animal requirements that 3 kg CuSO4 ha–1
be applied as a spray to pastures 4 weeks prior to harvest for silage
or hay, or alternatively that Cu be applied to the windrow once cut at
a rate no greater than 0.5 kg CuSO4 ha–1.
The addition of the other trace elements, I and Co to the Cu spray
further enhanced the conserved feeds’ mineral concentrations, and
this is likely to be reflected in enhanced animal mineral status.
Keywords silage; hay; copper; cobalt; selenium; iodine; animal nutrition
A05069; Received 8 December 2005; accepted 31 March 2006; Online publication date 10 July 2006
New Zealand Journal of Agricultural Research, 2006, Vol. 49: 273–284
0028–8233/06/4903–0273 © The Royal Society of New Zealand 2006
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