| |
Watch Your Withdrawal Periods
6/16/2008
Michael Fisher
Area Extension Agent
(Livestock)
Colorado State University Extension
Golden Plains
Area |
 |
| I have provided this information to assist you
with making informed decisions. If you have questions about this article or
suggestions on making this or other articles better, please click on the
buttons below. |
|
|
|
Do you know what the withdrawal period is for the various animal
health products that you administer to your livestock? For that matter, do you
know what a withdrawal period is established for?
As livestock
producers, we are the first line of defense in ensuring that the American meat
supply is a quality, wholesome, and safe product. To help meet that goal,
withdrawal periods have been established for many of the animal health products
that are used in livestock production. This is a period of time beginning with
the administration of a pharmaceutical product and lasting a set length that
has been pre-determined by the Food and Drug Administration (FDA). The idea is
that any pharmaceutical compound has a maximum allowable amount of residue that
can be in the meat product or milk. The withdrawal period allows a period of
time for the compound to be broken down within the animal following its
administration. Neither meat tissue nor milk can be used from an animal that
has a drug residue which exceeds the maximum residue limit (MRL) that has been
set for that given compound. In other words, the withdrawal period is an
opportunity for a treated animal to be in compliance with the MRL at the time
of harvest or milking.
The FDA has established the MRL for the various
medications based on several different locations within the animal. The residue
source that is examined is dependent upon what medication is being monitored.
As an example of the differences, Pfizer's Draxxin (active ingredient:
tualthromycin -18 day withdrawal) has a MRL of 5.5 parts per million (PPM) in
the liver; while Elanco's Tylan injection (active ingredient: tylosin - 21 day
withdrawal) has a MRL of 0.2 ppm in fat, muscle, liver, and kidney.
Pharmaceutical companies, under the FDA's guidance, have to conduct trials to
determine how much time it takes for a given compound's residue to be at or
below the assigned MRL following treatment of the animal. If the time needed
ends in a fraction of a day, the withdrawal period is expanded to complete that
day.
The label on the product is required by law to display the
withdrawal period on it. Likewise, a producer who uses a product is required by
law to follow the withdrawal period. So if you use a product that has a 28 day
withdrawal period and you sell the treated animal to be harvested ten days
after treatment you would be in violation of federal law. Should samples from
your animal's carcass have residue levels greater than the MRL for the product
that you used you can be held legally liable and can potentially face both
criminal fines and a jail term.
If you are knowingly marketing livestock
to an export meat market you may want to investigate the withdrawal period
issue a little deeper. Not all countries use the same formulas and/or
methodology to determine what the withdrawal period should be for the various
animal pharmaceuticals. As an example, many producers use Pfizer's Liqumycin LA
- 200 (active ingredient: oxytetracycline). In the US the FDA has established a
28 day withdrawal period for this product; however, in the Japanese market the
withdrawal period is 62 days. This is because Japan requires a much lower MRL
for the compound. So you could potentially be following all of the US
guidelines but intentionally market an unacceptable export product.
Another residue issue that can arise is when a producer feeds a product
and does not realize that it may contain something that is regulated. One
common cause of this in recent times has been a result of feeding distiller's
grain. Virginiamycin is allowed in ethanol production to control fermentation.
The MRL for this compound is quite high with 30 ppm in muscle, 120 ppm in fat,
60 ppm in liver, and 90 ppm in kidney allowed. With these high MRL levels most
cattle consuming distillers grains are not a problem in the US. However, the
Japanese have established virginiamycin MRL's of 0.1 ppm in muscle and 0.2 ppm
in fat, liver, and kidney. Also, it has been reported that some ethanol plants
have on occasion substituted other products in the fermentation process; which
later allegedly showed up as residue in the carcasses of animals that were
supposedly on an all natural program.
Considering all of the various
issues that can be associated with MRL's and withdrawal periods it is very
important that the livestock producer carefully monitor and record any
application of products with these classifications. If you wish to discuss this
subject further, Michael Fisher can be reached through the Yuma County
Extension office at 970-332-4151 or by e-mail at
mj.fisher@colostate.edu. |
Page Created and Maintained by: Perry D. Brewer, Area
Extension Agent (Technology Education/Youth)
6/18/2008 |
|
|
