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A practical guide to responsible antibiotic use

By Dr Dorothea Mostert, CS Vet
Antibiotic resistance and its link to the levels of antibiotic use in agriculture, especially in pork production, has become a global issue. It is true that worldwide, we are heading into an era where antibiotics will no longer be effective as more and more bacteria can withstand their effects. To what extent intensive protein production is to blame for this almost apocalyptic prospect, is debatable. What is not debatable is our responsibility to do the best we can to slow down the process in every way we can.
Establishing levels
As the saying goes, if you can measure it, you can manage it. The same goes for antibiotic use. The most common way of measuring antibiotic use is looking at your medication bill at the end of the month. This is not really a true measure of the amount antibiotics that goes into your production system.
A new system is being advocated in some countries that involve measuring the amount of milligrams of a specific antibiotic used per kilogram meat produced. Measuring antibiotic use in this way enables you to get a true reflection of the amount of antibiotic used in the production process. It is also the most accurate way to calculate use of antibiotics in one batch compared to another and from one farm or unit to another.
To do this, accurate record keeping is essential. Once you have determined these levels, it becomes possible to set a standard for you farm as well as a goal to work towards.
Correct usage of antibiotics
Using the correct dose of antibiotics, for the correct class of animal and adhering to the withdrawal time goes without saying. The duration of treatment should not extend the recommended period. The duration of treatment may differ when dealing with different scenarios, and is sometimes changed at the discretion of the veterinarian, in which case it should be followed.
Good systems should be implemented to ensure that the above points are adhered to, as this is often something that falls by the wayside.
If the decision is to use antibiotics, it should be evidence based. To administer antibiotics just because it might be necessary contributes to the growing resistance.
Disease surveillance
Not all bacteria were created equal and not all types of antibiotics work in the same way. This is why some antibiotics work moderately well against specific infections, some well and some not at all.
For this reason it is very important to do regular post mortems on mortalities, as well as regular sample taking, to determine exactly what disease you are dealing with and if possible what strain. This information will allow your consulting veterinarian to prescribe the best option for your situation, if antibiotic intervention is needed at all.
Diligently going through the whole herd on a daily basis to observe for any signs of disease is of critical importance. The earlier a situation can be identified, the quicker the response can be and the less medication should be needed to get it under control.
Resistance surveillance
Having an antibiogram, done along with routine sample taking at post mortems, will help with the choice of the correct antibiotic. It is not only a measure reserved for severe outbreaks, but a useful tool in successful day to day production.
When an antibiogram is done, the organism is cultured in a laboratory and exposed to various antibiotics. The ability of the organism to grow (or not grow) in the presence of the specific antibiotics will show whether it is still susceptible to that antibiotic or has become resistant.
When taking samples for microbial culture and antibiogram testing, it preferably has to be from an animal that hasn’t been treated with any antibiotic. The sample has to be taken in a clean manner, because any form of bacterial contamination can give a false set of results. It should be sent immediately, in a sample bottle, as a fresh sample and kept on ice.
Having a microbial culture and antibiogram done is the best way to see what you are up against. You don’t want to be caught using a knife at a gunfight.
The international organisation for animal health, the OIE, and the World Health Organisation (WHO) have released a document, ranking antibiotics with regards to critical importance. Antibiotics that are the only option for some severe diseases in human beings are reserved for human use only. The antibiotics available for veterinary use are classified into three classes. This brings about three tiers of antibiotics, only when there are no options available in a lower tier, a drug from a higher tier may be used, given that the choice is supported by evidence such as an antibiogram.
In feed medication
The use of low level antibiotics in feed contributes to the selection of resistant bacteria. When the decision is made to put antibiotics in feed, it needs to be scientifically justifiable.
A recent study has shown that there may be no benefit in routine fed medication when measuring the growth rate of weaner pigs within high health herd.
When the decision is made to go with in feed medication, the following strategies can be employed:

  • Instead of having medication for weeks on end, give one week on and one week off. This can halve the medication cost, as well as provide the immune system to mount an appropriate response against the diseases present.
  • Ensure that the right dose is given. To do this an accurate estimation of daily intake is extremely important. While under-dosing breeds resistance and will not have the desired effect, overdosing will be a big waste of money, it can have a negative effect on the animal and can also contribute to antibiotic resistance.
  • Opting for in-water medication if possible can result in a faster response time as there is no need for silos to empty before a medicated feed can be put through. Here it is also crucial to get the correct dose.

General hygiene and biosecurity
Good hygiene practices are the first step to reduce environmental bacterial load and the need for antibiotic use. A thorough routine of soaking, washing, disinfecting and down time between batches will prevent bacteria going from batch to batch.
When pigs are moved into a new compartment, especially from the farrow house to the weaner facility, they undergo various forms of stress. Disease occurs as a result of the interaction between the animal, its immune system, the environment and the pathogens present. Having a disinfected environment with optimal conditions will therefore give the pig a chance to spend his energy on adapting rather than fighting disease, resulting in better production.
Biosecurity is a combination of bio-isolation and biocontainment — keeping what’s yours to yourself and not let any new challenges enter your unit. It is of great importance, regardless of health status. This is achieved by having strict biosecurity rules that are adhered to by all, from the office staff to the unit manager right through to the driver.
Alternative therapies
There are hundreds if not thousands of products out there claiming to enhance immunity and reduce the use of antibiotics. Some of them are registered for use in food producing animals, some not. The vast majority rely on testimonials and wild claims, but offer no proper scientific data to support their claims.
If you want to try an alternative, make sure that it is well researched and discuss it with you veterinarian, as some of these products can have a negative effect on production, even if it is only increasing the cost of production.
While it is true that we will have to look to alternatives staring down the barrel of antibiotic resistance, do not shoot yourself in the foot. Be responsible when it comes to antibiotic use, do the basics right.
References available upon request.

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