A hatchery is the very earliest stage in chickens’ lives. Each type of contamination in this environment is a true threat to their health status. Hence, proper hygiene, disinfection and permanent monitoring in the hatchery are of paramount importance for an upcoming healthy flock.
By Colin Russell, consultant microbiologist, Aviagen, UK
While hatcheries have been in use within the poultry industry for many years, growing in size and complexity, many of the issues relating to hatchery hygiene have not changed. Our greater understanding of cause and effect and our ability to identify monitor and control disease causing agents has given us more robust methods to protect our chicks from infection but at the same time more challenges to overcome. Periodically even the best hatcheries will suffer from depressed hatch, higher first week mortality and a general reduction in chick quality. It is often attributed to ‘E coli’, ‘Pseudomonas’ or another microorganism used as a generic term for the condition. Post mortems of first week mortalities or culls often result in isolation of the above species and others from conditions such as omphalitis/yolk sac infection and inflamed/infected hock joints.
The first environment in a chicks life
If we consider the conditions we use in a laboratory to isolate these organisms and scale these up we have the same conditions as hatchers and setters provide, so perhaps the isolation of these organisms should not be a surprise. The real question should be, how do we prevent contamination of the hatchery initially, and how can we achieve microbiological control and prevent infection of the day old chick. Some of these microorganisms are of course true poultry pathogens: Aspergillus fumigatus, for instance, which will cause extensive lung infection and associated poor growth rate and high mortality in the day old chicks. Others, such as E coli, can act as a true pathogen but generally act as an opportunist pathogen. These organisms may infect the chick because they are present and are able to do so, not because they are obligate pathogens and need to colonise the chick to survive.
The growth of microorganisms can be represented graphically (Figure 1). This shows that bacteria in particular can multiply quickly with short generation times which, if unlimited, can result in one bacterium becoming over two million within seven hours. Obviously this growth rate does not normally occur outside the laboratory as growth conditions and nutrients are limiting, but a dirty hatchery following a hatch gives a good habitat for bacterial growth with adequate levels of moisture and nutrients in the form of chick fluff, egg debris, and other organic material.
If left uncleaned, these areas provide a source for further colonisation of hatchery air, water and drainage systems. For this reason hatcheries should be cleaned immediately after the hatch day using a proven hygiene programme which is monitored to prove efficacy. It is important that the hygiene programme is tailoured to the structure of the hatchery. A modern hatchery, constructed from composite panels, can withstand a much more aggressive hygiene programme with much more effective and aggressive chemicals, than an old hatchery constructed of wood and fibreboard. Electrical installations should also be considered as some caustic cleaners can make conduits, cables and switches brittle over time.
Effectiveness of disinfectant
Similarly, the hatchery equipment should be regarded as a factor when selecting cleaning chemicals, as stainless steel gives much more chemical options than aluminium, where chemical-induced corrosion can be rapid and severe. Once suitable chemicals have been selected for the hatchery structure, consideration should be also be given to the compatibility of the chemicals; for example, the detergent should be compatible with the disinfectant, as there is the risk that an incompatible chemical nature of the detergent can ‘knock out’ the effectiveness of the disinfectant.
In general, most hatcheries benefit from a three stage hygiene programme: Wash down, detergent application and sanitiser application. This can be detailed as follows:
Where there are specific problems in the hatchery, for example insect infestation, then an insecticide should be chosen which will be compatible with the general hygiene chemicals.
Clean water essential
Additionally, consideration should be given to water treatment coming into the hatchery which can introduce contamination to machines, in particular through the humidity systems. Some methods employed for this task are as follows:
Again, thought should be given to a combination of efficiency and corrosive effects of these methods dependant on hatchery structure and compatibility to the chemicals used in the hygiene programme.
There is a school of thought that there should be a shuttle programme for disinfectants, where two different chemical types are rotated alternately over a period of time to prevent bacterial resistance building up within the hatchery environment. While this strategy was applicable previously, we now have complex sanitisers on the market which have up to four different chemical classes combined in the preparation to produce a broad spectrum of biocidal activity. So far resistance to these types of sanitisers have not been reported.
Environmental monitoring of the hatchery should be used as a sole indicator of bacterial resistance, and any changes made based on the results generated and compared against a known monitoring standard with acceptable limits.
Many microbiological contamination problems are often assumed to be due to bacterial resistance to the chemicals employed in the hatchery, but these chemicals are only as good as the method and consistency of application. For instance, the application of a foam cleaner allows the operator to confirm that they have applied an even coverage over all areas; however the consistency of the foam is as important as the coverage. Foam should be thick with the consistency of shaving foam and have the ability to adhere to vertical surfaces for at least 20 minutes (see photos below).
The equipment used to produce the foam is key to the consistency; where inadequate foam is produced it can be enhanced by addition of a foam thickener or the introduction of additional air pressure to the foaming system.
The use of recycled water in the cleaning procedure should be avoided and, where this is designed into a cleaning system – for example some tray and basket washers systems, then water treatment such as chlorination should be employed as the water is recycled. Monitoring and control of chlorination levels is important from a potential corrosion and health and safety point of view.
Hygiene monitoring programmes
In order to establish the effectiveness of the hatchery hygiene programme and address potential contamination problems before they result in chick quality problems, a comprehensive monitoring programme and analysis of results is required. The monitoring results should be assessed for absolute microbial loading trends over time, including an analysis of seasonal fluctuations. Internal air samples should be compared to external air samples which are likely to enter the hatchery. This comparison also gives an indication of the current efficiency of hatchery air filtration where fitted.
Microbiological monitoring results
The results generated from a monitoring programme allow analysis of the hatchery hygiene programme and its ability to control potential pathogen introduction, and to minimise contamination from specific high risk points in the production system. The programme should highlight seasonal trends such as aerial fungi especially in hatcheries located in rural areas where a seasonal peak of aerial fungal spores can cause sudden and significant health problems in the day old chick.
While the access to laboratory facilities is advantageous, the hatchery can implement its own monitoring programme where a laboratory is not available by the use of rapid diagnostics, such as ATP measurement (equivalent to aerobic bacterial counts) and rapid culture techniques such as Petrie film. ATP in particular can be employed after cleaning to ensure prescribed standards are being met in real time and remedial action taken prior to the next hatch.
From the knowledge gained through the operation of monitoring programmes, changes in the hygiene programme in the form of chemical types or application methods can be implemented to ensure chicks hatch into a high hygiene environment which is pathogen free.
Source: World Poultry, Volume 30, No. 9, 2014