MARION ZOOLOGICAL
2006 LEAF EATER BATCHES
SELENIUM LEVELS
December 2006
Since our report from September
2006 I have
conducted more tests and thought it would
be a good idea to update you on my findings
and thoughts. As previously reported we found
a reasonable amount of consistency in the
selenium test results from our earlier production
runs as long as they were performed by one
laboratory using a single consistent AOAC
test method. However our feed mill manager
and some zoos were reporting a wide range
of values both on the low and the high side
using other laboratories and other AOAC test
methods.
For instance, some zoos using unnamed laboratories
and methods reported values as high as 1.5ppm.
Others reported values as low as 0.4 ppm.
Therefore,
a large random sample was pulled from our
December production run and sent
to three different laboratories all using
different AOAC methods. In one test, I selected
six small test samples from one single large
sample taken at the mill. I requested two
commercial labs and one university lab to
conduct tests on each of the two samples.
In other words I sent six identical samples
to three labs. Each lab received two identical
samples. I even tried to “fool” them
by giving different estimated normal ranges
of selenium (0.5 – 1.0 ppm) for the
first sample and an artificially high estimated
range for the second (1.0ppm – 1.5
ppm). The results (DM) are as follows:
| |
Sample 1 |
Sample2 |
| Lab 1 (AOAC Colorimetry) |
.74 ppm |
.71 ppm |
| Lab 2 (AOAC ICAP) |
.23 ppm |
.12 ppm |
| Lab 3 (AOAC ICAP) |
.79 ppm |
.79 ppm |
Note: Our routine quality control test results
range between 0.6 and 0.8 ppm on a dry matter
basis.
In the case of Lab 2, different samples
taken from the same production run were submitted
for re-test purposes. The results (DM) are
as follows:
| |
Sample 1 |
Sample2 |
| Lab 2 (AOAC ICAP) |
.16 ppm |
.16 ppm |
My conclusion is that there is quite
a large range of values reported by different
laboratories
on feed samples. Extraction methods and handling
are the probable causes of low values but
we do not understand how any laboratory could
report values higher than our quality control
range on a consistent basis no matter which
methods or extraction techniques were used.
I recommend that any laboratory values indicating
that our foods are out of our specified ranges
be aggressively challenged and re-tested.
Note:
Lab
1 is a national university recognized for
their selenium testing expertise.
Lab 2 is a nationally recognized laboratory
in the Corn Belt.
Lab 3 is a nationally recognized laboratory.
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SELENIUM LEVELS
September 2006
A few reports of findings from zoos in
the USA indicate that the selenium (Se)
level in our Leaf Eater Food is higher
than our specifications.
We are aware it does test higher than
our specifications and we have been studying
this issue for a while. Our published specifications
are 0.4 ppm on a dry matter (DM) basis.
Our test results of the five batches we
have produced this year are between 0.8
and 1.1 ppm on a dry matter basis. Routinely,
our quality control methods indicate the
test values to be between 0.6 and 0.8 ppm.
Although we are continuing to look for
reasons that would explain these higher
test values, we are not alarmed and we
are satisfied this is not the cause of
any harm or discomfort to any animals for
the following reasons:
