Feed Management - November/December 2017 - 28
28 ❙ FeedManagement
dairy cow trace
No single simple analysis can
accurately profile minerals in
BY HELEN WARREN
Mineral profiling is often used to assess deficiencies
and/or toxicities - as well to evaluate different dietary trace mineral sources and to investigate under
performance. While blood tests are probably the most
common method used to assess mineral status in ruminants, they may not necessarily be the most appropriate and are subject to limitations.
Tests can measure minerals directly, as well as
functional problems and/or proteins unique to the
mineral. Hence, there is often more than one test
for the same mineral with varying specificities.
With the development of techniques, such as inductively coupled plasma/mass spectroscopy (ICP/
MS), samples can be analyzed rapidly, accurately
and relatively less expensive compared with older
Whatever the sample tissue used, there are principle considerations when interpreting the results,
including age of the animal; prior and current health/
disease status; production stage and dietary intake of
the mineral in question, as well as the intake of antagonistic compounds.
Assessment can also be on an individual or
Sampling of tissues can be carried out ante- or
post-mortem, depending on the situation and what you
are trying to achieve. Liver and urine can be used anteand post-mortem, whereas milk is reserved for live
animals only. Additionally, post-mortem, ocular fluid
and bone tissue can be sampled.
There are obviously some tissues that are more
easily sampled, and others that would not be viable,
post-mortem. In live animals, whole blood and its
respective fractions (serum and plasma) is most commonly used. It is relatively non-invasive and can give
indications of deficiencies and/or toxicities. Despite
this, blood is not a particularly accurate reflection of
status for many important minerals as it is influenced
by disease and dietary intake.
Blood sample accuracy varies
Most trace elements are not static within the
body. They will be located in pools: a storage pool,
transport pool and functional pool. That said, not
all minerals have a recognizable storage pool.
www.WATTAgNet.com ❙ November/December 2017