New Zealand Journal of Agricultural Research abstracts
The effectiveness of copper fertiliser in maintaining the copper
status of deer at moderate to high pasture molybdenum contents
L. C. Smith
AgResearch
Woodlands Research Station
RD 1
Invercargill, New Zealand
chris.smith@agresearch.co.nz
M. F. Hawke
Bay of Plenty Farm & Pastoral Research
c/o NZ Forest Research Institute
Private Bag 3020
Rotorua, New Zealand
J. D. Morton
AgResearch
Invermay Agricultural Centre
Private Bag 50 034
Mosgiel, New Zealand
W. D. Catto
Ballance Agri-Nutrients
Hewletts Road
Private Bag 12 503
Mount Maunganui, New Zealand
Abstract Copper (Cu) deficiencies are an important
concern of the New Zealand livestock industry, particularly for deer.
Cu fertiliser application to pastures has been proven to be effective,
providing the particle size is suitable and the pasture has low
molybdenum (Mo) concentrations (<1 ppm). A field study was set up to
determine the effect of Cu fertiliser application on deer grazing
pastures of moderate to high Mo concentrations (2–8 ppm). Mobs of deer
(red × elk and red × wapiti weaners) grazed both Cu
fertilised and non-fertilised paddocks on farms near Rotorua (pasture
Mo 6–8 ppm) and in Southland (pasture Mo 1–2 ppm) over the winter of
2003. An initial application of solid CuSO4 (12–15 kg ha–1)
applied in April 2003 failed to elevate pasture Cu above an effective
level of 11 ppm due to large particle size
(97.8% > 2.0 mm) and slow dissolution. Liquid CuSO4
at 5–6.7 kg ha–1 was sprayed on
pasture in June/July, and grazed by the trial animals. This application
resulted in a significant increase in serum Cu (P < 0.05)
when compared to untreated controls (16.8 versus 9.1 µmol
litre–1 after 14 days at Rotorua and 11.6 versus
7.8 µmol litre–1 after 1 day in
Southland). At the Rotorua site, deer serum Cu levels in the mobs
grazing Cu fertilised pasture were maintained in excess of
15 µmol litre–1 up to the trial
completion in October 2003. In contrast at the Southland site, deer
serum levels in the Cu fertilised treatment started to decrease by
October 2003. The animal liver Cu levels at both sites were increased
by grazing the Cu fertiliser amended pasture for both the August (656
versus 158 µmol kg–1 fresh tissue, P
< 0.001) and October (362 versus 83 µmol
kg–1 fresh tissue, P < 0.01)
samplings. The Cu spray application increased pasture Cu concentration
for more than 3 months at Rotorua but only 2 months in
Southland. Despite the extremely high initial pasture Cu concentrations
achieved (>1000 ppm), there were no visible signs of animal health
problems with the animals grazing at the time of spraying. However,
further research is required to determine the effect of such high
pasture Cu concentrations on deer before a suitable level of Cu
application to pasture and animal withholding period can be
recommended. The results of this study showed that even at herbage Mo
levels ranging from 1–3 ppm in Southland and 2–8 ppm near Rotorua,
copper sulphate (5–6.7 kg CuSO4 ha–1) sprayed
onto pastures in mid winter resulted in the herbage Cu concentration
being increased to in excess of 100 ppm for 90 days. With this increase
in herbage Cu, the animal Cu intake from grazing these pastures was
sufficient to lift or maintain both serum and liver Cu levels in deer
for up to 4 months.
Keywords deer; copper; mineral nutrition; pasture
concentrations; serum Cu; liver Cu
A05010; Received 17 March 2005; accepted 29 November 2005; Online
publication date 28 February 2006
New Zealand Journal of Agricultural Research, 2006, Vol. 49:
45–54
0028–8233/06/4901–0045 © The Royal Society of New Zealand 2006
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