Feed Management - November/December 2017 - 31
FeedManagement ❙ 31
be used as a guide. Again, serum is useful for sodium
and potassium, although urine can also be used to
For the main trace elements, the liver is deemed the
most reflective of status but is not always a feasible option.
Copper can be detected in serum, in addition to whole
blood levels of superoxide dismutase, although the latter
responds more slowly to deficiency.
Plasma ceruloplasmin accounts for the vast majority
of copper in blood but, again, levels respond slowly until
marked depletion of stores has occurred. Combinations of
whole blood and serum selenium, as well as whole blood
glutathione peroxidase, can give a reasonable indication of
status, although liver is better. However, blood parameters,
especially serum selenium, are significantly influenced
by intake, including source of selenium. Serum zinc is
reduced in a deficiency but even "normal" values cannot
rule out a deficiency.
The levels of many trace minerals are affected by
disease as inflammation can increase circulating levels of
protein-bound minerals, such as ceruloplasmin.
Accuracy a challenge
There is no one simple analysis for the assessment of
mineral status of livestock. While techniques, such as
ICP/MS have significantly improved analytical efficiency,
the parameters tested may still not give an accurate impression of mineral status.
Various tissues can be tested for levels of mineral element and mineral-specific proteins. Liver appears to be
the tissue most reflective of status, but blood and blood
fractions are most commonly used. However, several
factors, including age and dietary mineral intake, affect
It's crucial to have an understanding of these factors,
as well as how minerals are stored and utilized within the
body, to accurately interpret any mineral analysis. ■
References available on request.
Dr. Helen Warren, owner of HW Consulting, achieved her Ph.D. from Bristol University. After working in academia,
she worked for a global animal health company. She is currently chair of the British Society of Animal Science
Industry Association, a registered animal scientist and certified Cow Signals trainer.
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November/December 2017 ❙ www.WATTAgNet.com