What is the difference between a dead egg and a contaminated egg?

Widely available, affordable and rich in nutrients, chicken eggs are one of the most important animal-based foods for global food security. For farmers, it is essential to provide safe, uninfected eggs to the public in order to avoid batches of poisoning in the population.

When infected, ingestion of this food can lead to death in the worst case. In this article you will find out what dead eggs and contaminated eggs are, and under what conditions this food can contaminate the consumer.

All about a dead egg

What is a dead egg?

A poultry egg is considered dead when it does not contain a living embryo.

It is an egg that has not been fertilised or has been fertilised but has not developed a viable embryo.

A dead egg can be distinguished from a fertilised and viable egg by checking for the presence of an embryo and monitoring its development during incubation.

Causes of egg death

There are many causes that can lead to the death of a poultry egg. These may include problems with egg laying, such as

  • Late or premature laying
  • Problems with fertilisation, such as a lack of sperm,
  • Problems related to inadequate brooding, such as inadequate temperature or humidity, insufficient ventilation or bacterial contamination.

Taking steps to avoid these problems and maintaining optimal incubation conditions will maximise the chances of successful hatching.

Identifying dead eggs: I tell you how

On farms, dead eggs can be identified by a series of visual and olfactory characteristics, such as

  • A discoloured or porous shell
  • A yolk that moves easily when shaken,
  • An unpleasant smell
  • Lack of embryo formation after incubation, etc.

Removal of dead eggs from the incubator or nest is essential to avoid batch contamination of other healthy eggs and to maintain optimal incubation conditions.

Risks of consuming dead eggs

Before consuming eggs, it is important to always check their freshness to reduce the risk of contamination and avoid health problems.

Can dead eggs contaminate consumers? Although minor, dead eggs can pose health risks when consumed. In addition, dead eggs have an unpleasant odour and taste, which may cause an aversion to eating eggs in general.

Contaminated eggs: what you need to know

Contaminated eggs

Contaminated eggs need to be identified to avoid several issues

What is a contaminated egg?

A contaminated egg is an egg that has been exposed to harmful bacteria, as in the case of Salmonella bacteria. Infection can occur at any point in the production of the egg, from laying to distribution. Ingestion of contaminated eggs can lead to serious health problems, such as poisoning, nausea, vomiting, diarrhoea and abdominal pain.

Egg contamination: how does it happen?

Egg contamination can occur in several ways. Firstly, a hen may carry bacteria such as Salmonella or Campylobacter and transmit these germs through the eggs laid.

In addition, if hens are kept in unsanitary conditions, they may lay eggs contaminated with faeces. Finally, if eggs are handled without the necessary hygiene precautions, they can also become infected. It is therefore important to follow preventive and food safety measures to reduce the risk of egg contamination.

How to identify a contaminated egg

It can be difficult to visually identify whether an egg is contaminated or not. However, there are ways to determine this. Farmers can use laboratory tests to detect the bacteria or germs in the egg. It is important to remember that farmers should follow good hygiene and biosecurity practices to minimise the risk of egg contamination.

Some companies have also developed machines that can detect contaminated eggs very quickly. The LaserLife® machine from Ecat-iD is revolutionising the incubation sector with modern technology that can process large numbers of eggs in record time.

Consumers should check the expiry date of the egg or perform a float test by placing the egg in water. If the egg floats, this may indicate contamination, as it means that air has entered the egg. Finally, if the egg has a strange or abnormal smell, it is best to throw it away to avoid contamination.

The risks of eating contaminated eggs

Can contaminated eggs contaminate consumers? Of course, YES. Eating contaminated eggs can lead to many health risks, such as so-called food-borne illnesses, food poisoning and other contamination-related diseases.

The risks depend on the type of contamination, which can be bacterial, viral or parasitic. The most common symptoms are nausea, vomiting, diarrhoea and fever. It should be noted that the risks are greater for people with weak immune systems, as the weaker the immune system, the greater the symptoms.

What are the differences between these two types of eggs?

The main differences

The main difference between a contaminated egg and a dead egg is that a contaminated egg may contain bacteria or viruses that can cause illness in humans if consumed.

In contrast, a dead egg is simply an egg that has not developed properly, usually due to inadequate incubation conditions. Although dead eggs should not be consumed, they do not pose the same risk to human health as contaminated eggs.

It is possible to distinguish between these two types of eggs!

A dead egg shows no signs of embryonic development inside its shell, while a contaminated egg may have a visibly clean shell but contain bacteria or viruses that can cause disease.

To identify a dead egg, simply apply the flotation method by placing the egg in water: if it sinks, it is dead; if it floats, it is potentially contaminated. However, it is important to note that most contaminated eggs show no outward signs and must be handled and cooked properly to avoid the risk of disease.


As with other producers of animal products, poultry farms have a responsibility to ensure food safety and that batches of eggs are not contaminated. For example, it is essential that they can distinguish between dead and contaminated eggs to avoid the risk of illness from the ingestion of harmful bacteria such as salmonella.

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