Understanding how to preserve the life of hatching eggs

Hatching eggs require careful management from the moment they are formed to the moment they hatch. Breeder farm conditions, egg handling conditions, incubation conditions… All these factors have an impact on chick embryo physiology and development, and consequently on the health and quality of new-born chicks. In this article, we examine the main factors that need to be considered to preserve the life of hatching eggs. 

From breeder farm to hatchery

Incubators provide the optimum conditions for hatching eggs to become high-quality chicks. However, it is important to look further than that. The health and quality of a day-old chick is influenced by the complete ‘history’ of its hatching egg, from breeder farm to hatchery. It is therefore necessary to protect eggs against biosecurity threats, temperature fluctuations and improper handling during egg formation at the farm, storage at the farm, transportation to and handling at the hatchery.  

1. Litter and nest management

The typical design of a breeding house involves a centre area filled with floor litter or litter nests. It is very important to keep the litter clean at all times to avoid potential contamination of the hatching eggs. The largest risk for the chick embryo comes from contamination immediately after the egg has been laid. As it cools down, the egg content retracts and suction from the outside to the inside occurs, meaning microorganisms can enter through the eggshell pores. If the environment is dirty, bacteria will gain entry to the egg. Eggs with dirty shells also carry harmful bacteria and are a biosecurity threat. 

Any form of contamination will have a big negative impact on hatching results and chick quality: 

• Weakened embryos
• Increased early embryonic mortality
• More exploders (‘bangers’)
• More dead in shell
• Increase in culls
• Higher first-week mortality

2. Egg collection and pre-selection

Laid eggs must be regularly collected to reduce the risk of breakage and contamination and all substandard eggs with, for instance, misshapen, cracked or thin shells must be removed. 

In addition, an increased frequency of egg collections is important for the eggs’ gradual cooling towards the ‘physiological zero’ (i.e. temperature at which embryonic development is slowed down). If an egg stays in the nest for too long, it increases the risk of a continued cell multiplication (more info under point 5). 

3. Egg disinfection and on-farm storage

Eggs can either be disinfected at the breeder farm or upon arrival at the hatchery. The purpose of disinfection is to prevent bacterial multiplication. Several practices for egg disinfection can be implemented (depending on the local rules and policies), such as: 

• Fumigation
• Spraying
• Fogging
• Washing (mostly used for duck eggs)

After the eggs have been disinfected, they can be stored in an environmentally controlled farm storage room until transport to the hatchery. If the farm has no dedicated egg storage room, eggs must be transported to the hatchery daily. 

4. Egg grading

Farm personnel conduct the pre-selection of hatching eggs, whereas hatchery personnel are responsible for the final egg quality control. A careful check of the incoming eggs’ external qualifications prior to incubation is strongly recommended. A good hatching egg should have the following characteristics: 

• It is free from any deformities.
• It has a good shell quality.
• It is clean.
• Its colour is uniform within its batch. 

5. Egg storage and recommended temperature profile

Hatching eggs are generally stored at the hatchery before they are loaded into the incubators. The total storage time varies, in some cases reaching 10 days or more. The V-flow diagram below (see figure 1) visualizes the temperature profile that should be followed: The hatchery’s egg storage room should be the coldest point along the breeder-farm-to-hatchery timeline. If there are uncontrolled temperature fluctuations in the process where specific points are warmer or cooler, then the embryo will be weakened, often resulting in an increased embryonic mortality, especially at the early embryonic stage.