New Zealand Journal of Agricultural Research abstracts
The effect of high pasture molybdenum concentrations on the copper status of
grazing horses in New Zealand
S. G. PEARCE
E. C. FIRTH
Institute of Veterinary, Animal and Biomedical
Sciences
Massey University
Private Bag 11222
Palmerston North, New Zealand.
N. D. GRACE*
AgResearch
Grasslands Research Centre
Private Bag 11008
Palmerston North, New Zealand
P. F. FENNESSY
AgResearch
Invermay Agricultural Centre
Private Bag 50034
Mosgiel, New Zealand
Abstract The objective of this study was to determine whether
Mo causes secondary Cu deficiency in pasture-fed horses. Twelve Thoroughbred
weanling fillies were divided into two groups and fed either high Mo pasture (8
to 15 mg Mo kg-1 DM) or a low Mo pasture (0.6 to 1.2 Mo
kg-1 DM) for 84 days. Both pastures contained 6 to 9 mg Cu
kg-1 DM. The animals were challenged with Cu over the last 14 days
to determine change in their Cu status to 1.0 mg Cu kg-1 liveweight
d-1 given orally three times a week. Copper status was assessed from
liver, plasma, blood cell, and plasma trichloroacetic acid-insoluble Cu
concentrations as well as the enzyme activities of plasma caeruloplasmin and
red blood cell superoxide dismutase. None of these indices was affected by the
increase in Mo intake. Horses grazing pasture high in Mo responded no
differently to Cu challenge than did those on low Mo pasture. The results of
this study suggest that Mo is unlikely to increase dietary Cu requirements and
induce secondary Cu deficiency at the Cu and Mo concentrations normally found
in New Zealand pastures grazed by Thoroughbreds.
Keywords copper status; molybdenum; pasture; horse
New Zealand Journal of Agricultural Research, 1999, Vol. 42: 93-99
0028-8233/99/4201-0093 $7.00/0 (c) The Royal Society of New Zealand
1999
PDF file of entire paper: medium quality (571K); (scanned from paper original: notes about this process)
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