Two main reasons for a huge drop in hatchability

Turning failure and the use of formaldehyde can critically affect embryo vitality, especially during the first seven days of incubation, when any inconformity is certain to result in a large drop in hatchability due to early embryo mortality. Frequently, the hatchery manager starts to worry that something is wrong on around day ten, when a lower CO₂ level comes to their attention, or when a higher percentage of clear eggs is observed during routine test candling. This will be confirmed in the hatchers when fewer live embryos hatch, resulting in a lower humidity peak and lower CO₂ production, with consequences for the ventilation rate.

The setter (and hatcher) climate graphs or recorded data should be checked to investigate how the incubation cycle performed. It is not usually possible to directly identify a problem due to a turning failure or formaldehyde effect. However, the slower build-up of CO₂ since start of incubation or the observation that the setter’s dampers – if they are controlled by a CO₂ sensor – are less open than normal are strong indicators of high embryo mortality during the incubation cycle. Embriodiagnosis can confirm the suspicion that there were problems at the start of the incubation cycle, indicated by a huge increase in early and middle embryo mortality.

It is important to check whether the drop in hatchability is seen in all hatchers loaded with eggs from a specific setter. Turning failure may occur in just some trolleys, resulting in decreased hatchability in some hatchers, while a total interruption in turning or excessive use of formaldehyde will generate a negative effect in all hatchers.

Advice:

• Check the turning system and intensify preventive maintenance after each transfer.
• Lubricate incubation trolleys after cleaning to ensure smoother turning with less risk of damage to the turning system.
• Check whether the turning system is running properly in all setters at least twice a day.
• Avoid using formaldehyde inside setters with embryos younger than four days / 96 hours, as this is lethal.
• Avoid using formaldehyde to disinfect empty setters after transfer, as residue may spread to a nearby setter starting its incubation cycle.
• Never use formaldehyde to disinfect a setter’s air entrance plenum.