Tighter controls around the world on in-feed antibiotics have increased the importance of disease prevention through vaccination and biosecurity. The change in legislation has resulted in new challenges for the poultry producer including the increased incidence of necrotic enteritis in broilers, which was previously controlled using ionophore feed additives.
The poultry farmer is constantly under pressure to drive down other diseases such as Salmonella, with the specter of legislation against new diseases such as Campylobacter always on the regulatory authority’s radar.
Biosecurity, at its best, offers poultry good protection against a wide range of diseases through exclusion of diseases from the housing. A visit to any great grandparent poultry housing will demonstrate the recognition of the need for good biosecurity. On the other hand, there is always a cost attached to this type of high-level biosecurity and so the layer and broiler farm have to combine good biosecurity practices with cost control.
At the heart of biosecurity are disinfectants and sanitizers. If used correctly, these products can make the difference between healthy productive birds and a poorly performing farm.
There is no best disinfectant
This shift in emphasis toward disease prevention has pushed the use of disinfectants and other biosecurity products to the fore. It has also raised the question of which is the best type of disinfectant to use. The answer is simple: there is no best disinfectant!
Each product has its own benefits and shortcomings. When choosing a disinfectant, the key is to understand the needs of the farm in question and the properties of the disinfectants available.
In order to work out which disinfectant provides the optimum solution, there are a few questions which need to be answered:
- Which type of disease organism needs to be controlled? e.g. bacteria, viruses (enveloped or non-enveloped), fungi
- What has to be disinfected? e.g. buildings, equipment, water, transport, personnel
- How can the efficiency of footbaths be improved? e.g. coping with extremes in temperature, high organic matter, etc.
In order to make a comparison between the various disinfectant types, it is important to find an unbiased source of information upon which to base a judgment.
Many countries have independent sources of information. In Europe, one of the best is provided by the German veterinary association’s website www.dvg.de, where a comparison can be made across various disease groups.
The tables show the range of dilutions approved by the DVG for products of each type of microorganism.
It is interesting to note that these concentrations do not agree with most of the manufacturer’s recommended concentrations. This is probably connected to the manufacturer’s wish to be more cost-effective than competitors. Recommendations are based on the product’s efficacy when used in ideal conditions. Note that the DVG tests are conducted at low temperatures and with a high organic matter loading. They therefore represent the worst possible environment in which a disinfectant can be effective.
Another problem for the farmer is how to compare products when they are all tested under different conditions. In general, the European tests are more demanding than the equivalent U.S. testing procedures. This is clearly demonstrated by comparing the approval rates by different authorities of one of the leading glutaraldehyde and quaternary ammonium salt disinfectants.
The failure of manufacturers to recommend the optimum concentration for their products could well be responsible for the common belief that resistance builds up against disinfectants and so changing the type of disinfectant is required. From our own experience, if the product is used at the “correct” concentration i.e. as recommended by an independent organization (such as the Department for Environment, Food and Rural Affairs in the UK and DVG in Germany), we have never seen resistance build up against a disinfectant.
No single disinfectant is suitable for every use
In a perfect world, all disinfectants would kill all bacteria, viruses and fungi on all surfaces without being dangerous in any way to humans, wildlife, equipment and vehicles. They would be active at all temperatures and not be affected by the presence of organic matter. However, we do not live in an ideal world, and no single disinfectant is suitable for every use! Regional variations in climate, farm-building materials, animal genetics and management all impact on efficacy.
One of the most testing environments in which to farm is Asia, where the climatic conditions are perfect for bacterial and fungal growth. In addition, large numbers of insects mean diseases can be spread quickly from farm to farm, increasing the disease challenge.
These conditions, and the extensive use of organic-based building materials, mean disinfectants with higher glutaraldehyde contents are highly suitable for this region. Different countries and regions may also prefer different methods of application, whether spray, foam or fogging. The farmer must match the disinfectant with the particular needs of the farm and not just buy on price!
There is one thing all disinfectants have in common: they will not work if they do not come into contact with target organisms. In other words, success in disinfection is dependent upon thorough cleaning. Time spent cleaning surfaces for disinfection is never wasted.
Choosing the most appropriate product can be confusing as manufacturers tend to claim that their products work in all situations. At best, some disinfectants are suitable in most applications, providing the correct concentration is used. The table can be used as a guide to the correct choice of disinfectants, but it is a generalization and therefore it is recommended that the supplier’s instruction be referred to.
The overriding rule is to clean first and then to disinfect. A suitable regime would involve the following sequence of events as there are no real shortcuts to ensure the process will be effective:
- Dry-clean – remove organic matter and dirt (mechanically/by hand)
- Wet-clean – apply a suitable detergent (alkaline- or acid-based) to remove the grime without damaging the object
- Clean down and rinse with water using suitable pressure washer equipment as appropriate
- Surfaces can be tested at this stage for presence of protein; re-clean if tests show the surfaces are still dirty
- Rinse with water
- Dry (if the surfaces are still wet the dilution of the disinfectant will increase)
- Disinfect – preferably dry surfaces to avoid diluting the disinfectant
- Rinse when necessary, or allow to dry
Recommended application rates and exposure times are important. Disinfectants need time to be in contact with the organisms they are to kill or destroy if they are to work effectively.
Your footbath disinfectant is probably not ideal
A footbath presents a unique disinfection problem. The disinfectant has to work in an environment where the temperature may change from day to day, the organic matter challenge continually increases and rain can further dilute the disinfectant solution. In these situations one would expect that manufacturers would be careful to advise users about “best practice”, but that is sometimes far from the truth. It is, therefore, quite likely that a farm’s footbath disinfectant is far from ideal. It may either be ineffective because of high organic matter loading, or too dilute because of rain. Alternatively, it may be too concentrated and wasting money!
The modern footbath allows the user to measure the amount of disinfectant and water to produce the recommended concentration. It will have a lid to stop rain diluting the disinfectant solution and will be simple to incorporate into the farm’s standard operating procedure. It will also allow footbaths to be auditable by having a removable label that shows the date of footbath was filled, type of disinfectant used, batch number and concentration of the disinfectant used, etc.
Some general rules and tips about footbaths and disinfectants:
- In general, a disinfectant should be used in a footbath at twice the concentration of that used for disinfecting buildings.
- Disinfectants containing glutaraldehydes will see their activity drop in low temperatures. However, the Department for Environment, Food and Rural Affairs and DVG tests are conducted at 4C so all disinfectants will work sufficiently well down to this temperature and lower. At higher temperatures glutaraldehydes become even more effective.
- All disinfectants are affected by high levels of organic matter, but oxidizing disinfectants are more affected than others and need to be made up in higher concentrations. They should also be changed more regularly (daily) to ensure that they are working effectively.
- If a footbath is allowed to freeze, some disinfectants will be denatured and should be changed.
- It is advisable to make sure the footbath is covered to prevent rain diluting the disinfectant.
- A pH test on the footbath’s disinfectant only tells the footbath’s pH and does not indicate whether the disinfectant is still effective.
Some manufacturers recommend pH testing to see whether the solution needs changing, but have never tested their product with differing amounts of organic matter and at various pHs using an independent test protocol (e.g. the Department for Environment, Food and Rural Affairs, DVG, EU). Without this type of test, the pH of a disinfectant containing organic matter is meaningless.
Understanding the properties of disinfectants can be a precursor to thorough disease-prevention protocol on any farm.