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Author: Jannie Maritz
The following article is a special collaboration from AFMA (Animal Feed Manufacturers
Association) www.afma.co.za
We thank their kind support.
BENEFITS OF ANTIBIOTICS USED IN FOOD
PRODUCTION
Antibiotics have been widely used in the livestock and poultry industries since
their discovery more than 50 years ago. They represent an extremely important
tool in the efficient production of animal products such as milk, meat and eggs.
At sub-therapeutic levels in diets, antibiotics improve growth rate and efficiency
of feed utilisation (see Table 1), reduce mortality and morbidity and improve
reproductive performance (see Table 2). At high levels (prophylaxis and therapeutic)
antibiotics help to prevent disease in exposed animals and to treat diseases
(Cromwell, 1999).
Antibiotics used in animals also improve the safety of food as healthy animals
result in a safer food supply through the reduction and elimination of certain
pathogens. They reduce the cost and improve the quantity of food production
through the more efficient use of natural resources which is critical to meet
the escalating nutritional and protein needs of a growing world population.
TABLE 1: Effects of anti-microbial agents
in the starter, grower and finisher diets on performance of pigsª. Adapted
from Cromwell (1999)
| |
CONTROL |
ANTIBIOTIC |
IMPROVEMENT
(%) |
Starter Phase (7-25 kg)
Daily gain, kg
Feed/gain |
0.39
2.28 |
0.45
2.13 |
16.4
6.9 |
Growing
Phase (17-49 kg)
Daily gain, kg
Feed/gain |
0.59
2.91 |
0.66
2.78 |
10.6
4.5 |
Growing-finishing
Phase (24-89 kg)
Daily gain, kg
Daily feed, kg |
0.69
1.50 |
0.72
1.47 |
4.2
2.2 |
ªData from 453, 298 and 443 experiments, involving 13,632, 5,783 and
13,140 pigs for the three phases, respectively.
TABLE 2: Reproductive performance in
a swineherd before and after total withdrawal of antibioticsª
| ITEM |
ANTIBIOTICS1963-1972 |
NO ANTIBIOTICS1972-1985 |
| Number of litters |
398 |
688 |
| Conception rate, % |
91.4 |
82.6 |
| Pigs born/litter |
10.8 |
10.2 |
| Live pigs born/litter |
9.8 |
9.3 |
| Average birth weight, lb. |
2.84 |
3.04 |
| Pigs weaned per litter (21 days) |
8.8 |
7.5 |
| Average weaning weight, lb. |
12.5 |
11.8 |
| Survival of live pigs to weaning, % |
89.7 |
80.9 |
| Incidence of MMA, %¹ |
< 10 |
66 |
ªCromwell (1999). The data are from a closed, specific-pathogen-free herd
at the University of Kentucky. Antibiotics were used in breeding, lactation,
starter, grower and finisher diets and for treatment purposes as needed prior
to 1972. Antibiotics were discontinued in 1972 and have not since been used
as feed additives or as injectables for treatment purposes.
¹Incidence of mastitis, metritis and agalactia (MMA) for the period 1972-1975
only.
THE ANTIBIOTIC DEBATE AND EUROPEAN BAN
As early as the 1960's the use of antibiotics in animal production began to
be criticised and this led to regulation of antibiotic use in the United Kingdom
(after the Swann Committee) and subsequently in the European Community and elsewhere
(McMullin, 2000). The fundamental decision taken by these countries was that
active ingredients approved for therapeutic use in human or veterinary medicine
would not be approved for non-therapeutic indications. In the 1990's new controversy
broke out over the use of these products. According to McMullin (2000), there
were a number of technical reasons for this:
- Resistance to antibiotics used in human medicine is increasing
- No new class of antibiotic approved for ten years
- There are more patients in intensive care and suffering immune deficiencies
McMullin (2000) however indicated that the political reasons might be more
relevant:
- Sweden prohibited the use of growth promoters in 1988
- Sweden and Finland joined the European Union
- Derogations to continue bans on growth promoters were running out
Various groups were forced to re-examine the perceived danger that the use
of antibiotics in animal feeds contributes to a reservoir of drug-resistant
enteric bacteria that are capable of transferring their resistance to pathogenic
bacteria (salmonella, campylobacter etc.), thereby causing a potential public
health risk. Although there remains little scientific evidence to document such
transfer, the EU suspended the use of Avoparcin (1997), Tylosin, Virginiamycin,
Zinc Bacitracin, Spiramycin, Carbadox and Olaquindox (1999). This leaves only
Avilamycin and Flavomycin still approved as antimicrobial growth promoters for
poultry. In April 2000, Schering announced that it was halting development of
Everninomycin, thus removing pressure for a similar suspension of Avilamycin.
These suspensions were effected under the so-called "Precautionary Principle".
The EU does, however, recognise that these suspensions cannot be definitive,
and are merely a temporary measure pending the analysis of information, particularly
risk quantification, collected to establish whether these products may continue
to be used safely (McMullin, 1999). There is also a current debate at the federal
government levels of the United States about tighter restrictions (Hooge, 1999).
In addition to several widely used anticoccidials in the EU, feed grade pharmaceutical
antibiotics remaining on the approved list are monensin, salinomycin, flavophospholipol
and avilamycin. None of these drugs, the European Commission believes, is currently
important in human medicine and so not an issue concerning the spread of human
pathogenic bacterial resistance.
Hooge (1999) hoped that a more scientific approach and a co-operative effort
would be used for future rule making on the antibiotic issue in other countries
(including South Africa) than has been used in Europe. Some balance has to be
achieved so that clinical antibiotic use in human medicine and dietary and therapeutic
antibiotic use for gain, feed efficiency and disease prevention and treatment
in animal production can continue in the future.
WHAT DO RELIABLE SOURCES SAY ABOUT ANTIBIOTICS
IN ANIMALS
Over the years, several task forces have studied the safety issue of antibiotics
and have basically concluded that there is no direct link between antibiotic
usage in animals and human health (Cromwell, 1999). The following summary was
prepared as a courtesy of Elanco Animal Health (14 June 1999).
The National Research Council
There is no crisis over the use of antibiotics in animals.
"The committee concludes that the use of drugs in the food-animal production
industry is not without some problems and concerns but that it does not appear
to constitute an immediate public-health concern…….." 1988
report requested by the United States Department of Agriculture and the Centre
for Veterinary Medicine.
The HAN Foundation
Antibiotics in animals have not compromised human health.
"Sofar, AGP [antibiotic growth promoter] use did not compromise the human
therapeutic use of related antibiotics. Sofar, epidemiological data do not show
an increase of infectious diseases as a result of the use of AGP's."
The HAN Foundation (stichting Heidelberg Appeal Nederland) is an independent
non-profit alliance of scientists and science supporters, located in the Netherlands.
The "Swedish Experiment" Critiqued
by Professor Jaques Viaene
Banning feed-additive antibiotics is counter-productive.
"The Swedish ban of antimicrobials for in feed use without prescription
and the Animal Protection Act have lowered production efficiency and increased
costs. [p. 4]"
"…the economic burden has been heavy for consumers and for farmers,
through increased feed use, loss of production and increased use of therapeutic
levels of antibiotics. [p. 4]"
"… in effect, it has been the consumers and the farmers who have
paid for the Swedish experiment [p. 19]"
Report by Prof. Jaques Viaene from the Ghent University, Department of Agricultural
Economics in January 1997.
The World Health Organisation
Resistance has emerged with little documented impact on humans.
"The use of fluoroquinolones in food animals has led to the emergence of
fluoroquinolone-resistant Campylobacter and of Salmonella with reduced susceptibility
to fluoroquinolones. There has been little documented impact of this resistance
on human health to date, but there is concern about the potential human health
consequences if resistance were to increase and spread [p. 8]"
Report by World Health Organisation's Division of Emerging and other Communicable
Diseases Surveillance and Control, summarising a meeting on 2-5 June 1998 in
Geneva, Switzerland.
PRUDENT USE OF ANTIBIOTICS IN ANIMALS
On 23 February 1999 the World Veterinary Association (WVA), the International
Federation of Agricultural Producers (IFAP), and the World Federation of Animal
Health Industry (COMISA) announced a new set of global principles to ensure
responsible and prudent use of antibiotics in animals. The three organisations
indicated that they are committed to implement the principles in the daily practice
so that antibiotics can be used to improve animal health and welfare without
sacrificing human health.
Some of the key basic principles for prudent use of antibiotics are:
- Antibiotics are health management tools which are licensed to enhance good
husbandry practice for the purpose of disease prevention, disease treatment
and production enhancement. They are a complement to these good husbandry
practices and should never be used to compensate for or mask bad farm and
veterinary practices.
- Codes of good practices, quality assurance programs, and education programs
should promote the responsible and prudent use of antibiotics.
- Professional supervision, particularly by veterinarians, and record keeping
are essential in the use and control of antibiotic products.
- Antibiotics used for therapy should be used for as short duration as possible,
but for as long as needed and at the appropriate dosage regimen, and attention
should be paid to label instructions.
- Continuous monitoring of the effects (positive and negative) of antibiotics
after this use should be conducted in order to adapt the use pattern very
promptly.
The principles also recognise that alternatives to antibiotics, provided they
are scientifically proven to be efficacious, are needed as an important part
of good husbandry practices.
ALTERNATIVES TO ANTIBIOTICS
The removal of antibiotic growth promoters from most feeds within the UK has
resulted in the search for "natural" and "safe" alternatives
(Ratcliff, 2000). For improving poultry performance, for disease prevention
and treatment and for reducing feed costs, a variety of commercial products
are available for use in combination with or as alternatives to antibiotics
(Hooge, 1999).
Alternatives to growth promoters need to be properly evaluated and due consideration
given to the quality, safety and efficacy of each product. It is unlikely that
a single product will merge as a direct replacement for the registered effect
of antibiotic growth promoters. It is more likely that a combination of products
may be considered together with a review of the various stress factors that
may affect performance and disease, including nutrition, environment and management
practices (Ratcliff, 2000).
Feed compounders in the EU are not expecting a quick reversal of the bans, which
was scheduled for review at the end of 2000. Rather, they are expanding their
use of a wide range of non-pharmaceutical, growth enhancing additives. These
additives include organic acids, probiotics, nucleotides, oligosaccharides,
enzymes, betaine, mineral growth promoters and 'botanicals' or plant extracts
including many traditional herbs and spices. 'Nutraceuticals', 'functional foods'
and human homeopathic remedies also are appearing in animal feeds.
Jannie Maritz 0OTK Feeds, PO Box
135, Isando 2123
REFERENCES
Cromwell, G.L., 1999. Safety issues, performance benefits of antibiotics for
swine examined. Feedstuffs, 7 June 1999, p.18.
Hooge, D.M., 1999. Antibiotics and their alternatives for poultry examined.
Feedstuffs, 17 May 1999, p.59.
McMullin, P., 2000. The future of Antimicrobial Growth Promoters: Alternatives
for poultry production in the new millennium. International Poultry Production.
Volume 8, Number 7, p.30.
Ratcliff, J., 2000. Antibiotic Bans - A European Perspective. Proceedings of
the AFMA Symposium on Improving Animal Performance through Nutrition. Pretoria,
South Africa, p.128.
Author: Jannie Maritz
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