Salmonella testing for egg producers and processors
The following guidance outlines how accreditation holders can demonstrate compliance by conducting environmental Salmonella testing on-farm or at processing facilities during each accreditation period.
Effective Salmonella Monitoring for Small Egg Producers
When Salmonella is present in a flock, not all birds will shed the bacteria at the same time or in equal amounts. During the early stages of infection, shedding may be intermittent or confined to a small number of birds. As a result, testing that relies on a small or unrepresentative sample can return false-negative results, providing a misleading indication of flock health.
To achieve accurate results, sampling programs should be designed to reflect the flock’s overall condition as closely as possible. Testing clean, intact shell eggs is not recommended because the likelihood of detecting Salmonella on uncracked, visibly clean eggs is extremely low. Such testing does little to reveal whether the bacteria are present in the flock or the production environment.
Instead, environmental sampling offers a more reliable and practical approach. Collecting representative samples of litter, dust, and faecal material from within poultry housing provides a more accurate picture of the flock’s Salmonella status. These materials are more likely to contain traces of the bacteria, if present, and therefore provide a sound basis for assessing risk and guiding control measures.
By implementing representative sampling practices, egg producers can strengthen their biosecurity programs, demonstrate compliance with food safety standards, and contribute to a safer egg supply chain.
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What samples should I test?
Testing waste eggs such as cracked, dirty, or otherwise unacceptable eggs that are typically discarded during packing can serve as a reliable indicator of whether Salmonella is present in the farming environment.
In addition to waste egg testing, other environmental sampling methods may be used, such as boot swabs of bird housing areas, and manure belt drag swabs.
Regardless of the method used, it is essential that the sampling approach is effective in detecting the presence of Salmonella Enteritidis (SE).
If you are a part of the National Salmonella Enteritidis Monitoring and Accreditation Program Guidelines (NSEMAP) or follow any other industry testing guidelines e.g. Australian Eggs, its important you follow their testing recommendations.
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How do I collect a sample?
Egg Pulp
A sample can be taken out of the waste bin/bucket at the end of the day’s production. It can include smashed eggs with bits of shell and eggs discarded throughout the process, from collection to grading.
The sample is to be collected in a sterile jar which can be purchased through your preferred laboratory.
Using gloves, fill up the 125mL jar with the waste liquid (ensuring you have obtained a proportionate pulp sample) seal with the lid securely and label the sample with a permanent maker with where it was samples from and the date.
Boot Swabs
Boot swabs are a simple and effective way to check for Salmonella in poultry environments. They involve wearing sterile boot covers and walking through areas where birds roost and roam, like poultry sheds, houses, or outdoor ranges. As you walk, the boot swabs pick up material like dust, faeces, and litter from the ground, which can then be tested for Salmonella.
This method is useful as it collects samples from a wide area and reflects the overall cleanliness and contamination level of the environment. It’s easy to do and doesn’t require specialised equipment, making it a practical choice for routine monitoring.
For more information on how to conduct a boot swab, along with other helpful resources you can find links below:
https://www.australianeggs.org.au/for-farmers/resources/food-safety
Transport
All samples collected must then be stored and transported under chilled conditions to your laboratory.
The laboratory will require you to complete a submission form containing all the relevant information for the sample. Ensure you let the laboratory know you are testing for Salmonella and that if your sample tests positive, you require further confirmation on what type of Salmonella it is.
Determining the type of Salmonella is important as some are more serious than others.
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When should I test?
The best time to test is when birds are most likely to shed Salmonella. These are times when the bird is under stress such as commencement of laying (sexual maturity around 16 – 22 weeks of age) or moulting.
Determining your business risk by conducting an assessment is important for deciding how often environmental testing should be done.
A risk assessment helps identify factors that increase the chance of Salmonella contamination, focussing on key areas such as:
- Seasonal factors, as warmer months, may increase Salmonella survival and spread.
- Rodent, bird, and insect activity.
- Flock health and production indicators, such as mortality spikes or signs of compromised bird health.
- Extreme weather events, which may stress birds or increase exposure to environmental contamination, e.g. overflow into production ranges.
- Regional SE prevalence in surrounding farms and the broader poultry industry.
- The source of replacement layers. Some suppliers may have an increased risk of birds being infected with Salmonella due to their business activities. For example, produce agencies dealing directly with the public, may have lower biosecurity controls and pose a higher risk than sourcing birds through recognised or certified breeder farms.
By understanding these risks, you can set a testing schedule that’s appropriate for your farm’s specific conditions. This ensures resources are used effectively while still protecting food safety.
At a minimum, testing is required to be conducted during each accreditation period (annually).
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Where do I send my samples?
Samples need to be tested at a NATA accredited laboratory.
You can search for accredited laboratories on the NATA website using “Salmonella” as the keyword. This will return a list for all laboratories in Australia and you can then filter to show only Queensland. You will then need to contact the laboratory to determine if they are approved to test Salmonella on egg or egg products.
As of June 2023, the following commercial laboratories were approved for Salmonella testing on eggs or egg products via the NATA website:
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How do I send my samples?
Most laboratories offer a delivery service at a cost if you are unable to deliver them directly to the laboratory yourself. Talk to the laboratory about what services they provide to best suit your needs.
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How much does testing cost?
Testing costs vary between laboratories. It is recommended that you obtain pricing from multiple laboratories if possible and come to an agreement on the cost with your chosen lab before proceeding.
Keep in mind – if Salmonella is detected in your samples and requires confirmation of the type, this will incur additional costs as more tests will need to be undertaken by the laboratory.
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Testing is expensive, can I pool my swab samples into one?
Yes, testing costs money but not testing and monitoring your flock correctly could cost your business more and possibly impact the whole industry. Boot swabs should be used in one area only; A pooled boot swab sample may consist of multiple boot swabs taken in a single shed/area into one sample. Walking through different bird sheds or housing areas may spread potential disease further. To maintain biosecurity practices, ensure you are not spreading potential contamination to other bird housing.
Some laboratories will accept a pooled swab sample, however there are some key points that need to be considered:
- A maximum of three boot swab samples are to be pooled together to form one sample. The testing laboratory must be made aware that the sample is pooled to ensure the correct testing method is used
- Samples from the same sample area can be pooled together e.g. shed one samples can be pooled together in one container or bag and shed two samples can be pooled together in a separate bag or container. This ensures that any detection can be clearly linked to the site it was taken from and affected sheds can be identified.
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What do I do with the results?
You will receive a final report from the laboratory once testing is complete. Read this report carefully and if Salmonella is detected, check what type it is. If you need help interpreting your results, Safe Food is happy to assist. You can email info@safefood.qld.gov.au or call 07 3253 9800. Alternatively, reach out directly to a Safe Food Officer if they have visited your site before.
Based on your test results, it may be a good time to review your farm controls to ensure that you are managing all the risks associated with Salmonella.
Regardless of the result (positive or negative), your laboratory report must be supplied to Safe Food and kept as a record to show at your compliance audit. You can email it to info@safefood.qld.gov.au.
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Why is testing necessary?
In early 2023, Queensland recorded its first ever detection of transovarian SE on a commercial egg farm. The importance of conducting targeted sampling has therefore never been more important, to not only protect your business, but the egg industry at large.
SE poses a significant risk to Australian egg producers due to its potential to cause serious foodborne illness, and it has implications for both domestic and international markets due to the potential transovarian transmission. Transovarian transmission means the bacteria can infect the developing egg inside the hen, so the chick or the egg itself may already be contaminated before it even leaves the hen’s body. This makes it harder to detect and control because the contamination is internal, not just on the eggshell.
Following an outbreak of SE in New South Wales in 2018/2019, the Queensland egg industry and Safe Food developed the SE Prevention Plan. Routine testing was included a part of the Standard Operating Procedures for this plan. While Safe Food initially adopted an educational approach with accreditation holders in relation to this, now SE has been found in Queensland, the risks have changed and the need to test is more critical.
Safe Food is committed to working with you to manage the risks of Salmonella and ensure Queensland’s egg industry remains sustainable.
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Example sampling plan
Outlined below is an example of a sampling program for an Egg Farm highlighting when to test and the purpose of the test. The goal is to detect Salmonella as early as possible before eggs enter the market and to continue monitoring throughout the laying period to verify ongoing control.
- Point-of-Lay Testing (This could be done by the Breeder Farm and a declaration provided with replacement layers)
Timing: Approximately 2–3 weeks before the onset of lay (typically around 14–16 weeks of age).
Purpose
Detects Salmonella before egg production begins.
Allows time to implement corrective actions before eggs are collected for sale.
- Early Lay Testing
Timing: Within the first 4–6 weeks of lay.
Purpose:
- Confirms that Salmonella control measures have been effective after birds have moved into production housing.
- For producers who rear their own birds – it Identifies any contamination that may have occurred during transfer from rearing shed to layer shed
- Routine or Periodic Monitoring
Timing: Every 12–15 weeks during the production cycle (or at least once per year for very small flocks).
Purpose:
- Provides ongoing assurance of flock status.
- Detects new introductions of Salmonella from environmental sources, wild birds, rodents, or feed.
- Post-cleaning and Disinfection Verification
Timing: After depopulation and before a new flock is placed.
Purpose:
- Confirms that cleaning and disinfection procedures have successfully removed Salmonella from the environment.
- Reduces the risk of carry-over infection to the next flock.