Why In-Feed Antimicrobials?
Introduction
Like people, animals can become ill and may need
treatment for a bacterial infection. In this situation a veterinary surgeon
may decide to prescribe a course of an antibiotic.
Why treat?
In modern livestock production, animals are often kept
under environmental conditions which are as balanced as possible to assist
health protection and growth. This means that there are often large numbers
of livestock in the same protective environment.
If disease affects these animals, the pattern is that a
small number may be infected and showing symptoms of disease while others
may be incubating the disease but not yet showing symptoms. Because it is
impossible under normal conditions to differentiate between these groups it
is normal to give therapeutic treatment to all the affected and in-contact
animals (sometimes technically termed "metaphylaxis").
It is often forgotten that for the livestock producer,
the use of antibiotics is a last resort. There is no NHS for animals and the
use of such products is very expensive for farmers. Therefore, their main
interest and that of their vet is to use every other possible avenue to
prevent and control infection before it can devastate their animals and
cause significant loss.
Why in-feed?
For very small groups of animals or animals kept
individually it is possible to use individual oral dosing of the animals or
to inject the animals with the appropriate dose of antibiotic. With larger
groups of livestock this becomes impractical and therefore other dosing
systems are essential.
Where individual dosing of animals becomes impractical,
the only systems that are suitable for large groups are drinking water
medication or in-feed medication. Many producers prefer water medication but
this usually requires a relatively complex system of dosing apparatus and
ensuring that the water supply line and tanks are free of any matter that
may cause deterioration of the active ingredient.
Particular attention has been focused on the
administration of substances “in-feed”. It is important to remember that
there are many positive, animal-friendly, reasons for supplying medicines in
this way:
-
Freedom from stress - compared to injection or oral
dosing, there is no stress to animals or staff. In large groups of
animals individual dosing can be a difficult exercise, potentially
resulting in injuries and death to the animals being treated and to the
farmers or vets administering the medication.
-
Universal suitability - while other systems, such as
water medication, can be very effective in some units, only in-feed
medication is equally appropriate to all sizes of unit and all types -
intensive or extensive.
For all the above reasons the use of in-feed medication
is still the most widely used and has fewer management problems than other
systems. In the presence of disease, or where disease is suspected, or based
on previous experience the disease is imminent, the veterinary surgeon
supplies a prescription to the feedstuff manufacturer and the appropriate
medication can be supplied during the manufacture of a special batch of
treated feed.
What controls?
Before an antibiotic is allowed to be marketed for animal
use, it has to be approved according to very strict European criteria on its
quality, efficacy and safety.
Growth promoting antibiotics (sometimes known as
digestive enhancers) are not permitted for use in the EU: the category
within the legislation under which they used to be authorised was removed on
1 January 2006.
Antibiotics are available only with the authorisation of
the veterinary surgeon. The difficulties of administration to groups of
animals, as explained above, have meant that a high proportion of
therapeutic antibiotics for livestock are supplied in the feed.
All premises that are involved in their incorporation
into feed are licensed for the purpose and are subject to inspection.
Similarly, the veterinary surgeon and the farmer have to ensure that he has
full records of usage of antibiotics, which again are subject to inspection.
As a result of all these checks and balances the illegal
use of any in-feed antibiotic in the UK is negligible and this is also
controlled by a comprehensive surveillance scheme analysing foodstuffs such
as meat, milk and eggs from both UK produce and imported produce. for
residues derived from the use of veterinary medicines. The results of the
surveillance schemes are published by the Veterinary Medicines Directorate
(VMD). They demonstrate that British farmers use medicines responsibly.
Nevertheless, the animal health industry has shown a
leadership role in the responsible use for example, through its
participation in the
Responsible Use of Medicines in Agriculture Alliance (RUMA), established
in 1997.
RUMA has published species specific guidelines on the use
of antibiotics, which have been updated subsequently to ensure they are
up-to date. The aim is, by encouraging best practice in animal husbandry, to
reduce the need for antibiotic treatment, with antibiotics being used ‘as
little as possible, but as much as necessary’. The RUMA concept has been
mirrored in the EU by the formation of
EPRUMA (European Platform
for the Responsible Use of Medicines in Animals).
In recent years there has been increasingly vociferous
concern expressed about the use of antibiotics in livestock. This has been
linked to the increasing levels of antibiotic
resistance in man. However, it is clear that the main bacteria which are
of concern in human medicine are unrelated to bacteria which are found in
animals and in most cases animals are not the source of human problems.
Where resistant bacteria could be theoretically passed
from animals to man, risk assessment studies are showing that the risk to
man is very small.
Much of the resistance to antibiotics in man is hospital
derived, where the patient has received the resistant infection during
hospitalisation, and the bacteria have developed resistance as a result of
antibiotic usage within human medicine and not as a result of antibiotic use
in animals.
Conclusion
Antibiotics used in feed are a precious resource and, if
used responsibly, will continue to assist in the provision of healthy,
affordable food for the human population. Administration in feed provides an
ideal way to treat groups of animals, extensive or intensive, and is subject
to extensive regulation.
Although there is much concern about the development of
resistance to antibiotics, careful, judicious use
of these products will prolong their life and that of the recipients. The
most widely used class of antibiotics in animal populations are those that
were the first discovered over 50 years ago. It is tempting to speculate why
this is so, and why resistance is not a major threat to most livestock
populations. Perhaps it is because most livestock are only a few weeks, or
months, of age when they are processed for food. Any resistant bacteria, in
the main, disappear from the farm and the next batch of animals is populated
by totally susceptible bacteria. This process contrasts markedly with the
situation in the human population where carriers of resistant organisms may
remain in the community for a very long time.
Finally, the livestock producer has gone to great lengths
to provide optimum environmental and disease control measures to minimise
the possibility of disease in his animals or poultry. There is no substitute
for the highest possible standards of husbandry and, providing they are
allowed to compete on equal terms with the rest of the world, the UK
producer will use in-feed antibiotics in the most responsible way, ably
assisted by their veterinary surgeon.
Printer friendly version here
Updated June 2010
(For information on anticoccidials see
NOAH briefing document 13 - Anticoccidials) |
