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Commonly,  hatcheries use the “percentage of Hatch” as key performance indicator (KPI). However, the percentage of hatch is a general indicator and does not provide the full picture of the performance when assessing the impact of a candling system or of an in ovo vaccination process.

For an In ovo vaccination performance control in production, the “difference between injected eggs and hatched chicks” needs to be also monitored. In other words, in addition to the % of hatch, the percentage of “Non-Hatched Eggs” need to be monitored on a daily basis. 

The average percentage of Non-hatched eggs varies from 4 to 6% depending on the hatchery, type and accuracy of the candling, age and sanitary status of the vaccinated flocks. If a deviation of the expected hatch happens, the difference between injected and hatched will clarify if the deviation happened before or after the transfer. That it is also useful to control the performance of candling systems.

On the other hand, to analyze deeply an increase on late mortality or to compare two different treatments at transfer time (for instance in ovo versus  non in ovo), the percentage of hatch and the difference between injected and hatched, will lead also to misinterpretation.


Therefore, an indicator able to discard incubation factors that can affect late mortality but are not linked to in ovo itself is required. This indicator is named “Hatch of viables”.

In other words, “hatch of viable” will exclude those non-viable embryos developed up to the transfer that would die in all different cases (malformation, head over the wing, etc.), and it will only take into account those late viable embryos that could be influenced by the treatment itself. 

Consequently, the percentage of hatch of viable is the best indicator to verify the eventual impact of an in ovo treatment, expressed by the number of fully valid day old chicks compared with the number of embryos potentially valid at the in ovo time, and not compared with the total number of eggs of each group.

In this context, deeper analysis through Hatchability Assessment inside the C.H.I.C.K Program services by regular necropsies of non-hatched eggs is paramount to calculate the “Hatch of viable” indicator and control In ovo process performance.