Producing safe eggs
Eggs are a food product that should be produced, graded, packed and distributed to minimise any potential food safety risk.
Eggshells are porous and, if handled incorrectly, may allow bacteria to be drawn inside the egg, whether the shell is cracked or not. Dirty eggs, even with eggshells intact, are a food safety risk.
If an egg's shell is cracked, particularly if the membrane inside is broken, bacteria can easily form inside and grow.
Egg producers, processors or transporters must have a system in place to reduce the risk of eggs being contaminated by bacteria.
In Queensland, there are certain responsibilities that you must comply with under the Food Safety Scheme for Eggs and Egg Products (Egg Scheme). The main requirements of the Egg Scheme make it illegal to:
- supply cracked eggs
- supply dirty eggs
- supply unpasteurised egg pulp
- supply eggs and egg products without an accreditation.
The Egg Scheme applies to producers, processors or anyone operating under a preferred supplier arrangement for eggs.
Salmonella is the main food safety pathogen associated with eggs. The illness caused by this bacterium (salmonellosis) can affect anyone.
There are over 2500 different types of Salmonella and they can be found in many different environments. It is able to survive in dry environments and can grow in wet environments. Birds usually become infected by ingesting infected matter such as faeces, soil or feather dander. Hens that have been exposed to and infected with Salmonella will often not show any signs of infection.
Salmonella can enter an egg farm in many ways, including through:
- day-old or pullets that enter the farm
- insects and rodents
- wild birds
- contaminated feed
- contaminated water
- other animals, including livestock and pets
- vehicles and equipment.
Birds infected with Salmonella can shed more into the environment, quickly spreading it to the rest of the flock. If eggs are laid in an environment contaminated with Salmonella, there is a higher risk that it will contaminate the shell.
Ensuring your farm has a biosecurity plan in place can help to reduce the risk of Salmonella entering your property.
Reducing the risk of Salmonella
Salmonella may contaminate eggs by movement of bacteria through the shell (e.g. when the shell is dirty or damaged). Once the bacteria enters the egg, it can quickly grow to levels that may cause illness. You can reduce Salmonella risk by:
- discarding cracked and dirty eggs
- cleaning eggs using an approved method during the grading process
- using approved egg wash and sanitiser products
- storing and cooling eggs at recommended temperatures
- not re-using cardboard egg flats
- having drinkers and feeders positioned to minimise any contamination from droppings
- using nesting material, replace regularly
- keeping clean and dirty eggs separate
- having a good rodent control program in place
- cleaning nest areas frequently
- having on-farm biosecurity practices in place.
The Code of practice for shell egg, production, grading, packing and distribution (PDF, 230KB) provides more detailed information.
Salmonella enteritidis (SE) is a type of Salmonella that can infect the egg during its development – through vertical transmission from an infected hen to the egg. This type of Salmonella is not endemic in Australia and any food poisoning arising from SE has been the result of contamination while overseas.
A number of countries have egg quality assurance programs in place and will not allow the importation of eggs from other countries, including Australia, unless they are able to prove they are free of SE through a monitoring program.
Currently, Australia does not have a national SE monitoring program. Queensland has its own Salmonella enteritidis Monitoring and Certification Program (PDF, 325KB) while Victoria and New South Wales have a joint Salmonella enteritidis monitoring and accreditation program.
Floor eggs are eggs laid outside of the nest. Floor eggs pose a high risk of contamination as they are more likely to be laid in an unclean environment.
To help reduce floor eggs:
- place pullets in the laying facility a couple of weeks before they are expected to start laying so they are used to their new environment and nests
- have the nests in darker areas
- make sure there are enough nest boxes and adequate space for all hens
- do not have dark places or shadows in the laying house (other than the nest) as this may encourage floor eggs
- have nests placed so they are easily reached by hens.
Advice for keepers of backyard poultry
To reduce the risk of Salmonella infection from eggs produced at home:
- always keep your nest boxes and poultry housing clean – the cuticle of the egg is not fully developed when first laid and can quickly absorb any bacteria into the shell if laid in a dirty environment
- discard cracked, dirty and floor eggs
- collect eggs daily
- don't wash your eggs with water, if needed use a clean, dry abrasive cloth and discard or sanitise after use
- cook eggs thoroughly
- always wash your hands before and after collecting eggs and handling hens
- have a rodent control program in place.
If your bird is unwell and has been administered medication from a veterinarian, discard any eggs that are laid by that hen while it is taking the medication and for about 4 weeks after treatment has ceased.