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Principles of single-stage incubation (4)

Part 4: Optimise your incubation performance by means of CO₂ control During incubation, embryos are consuming oxygen (O2) and producing carbon dioxide (CO2). With single-stage incubation, one can apply a ventilation controlled CO2 profile instead of venting at a constant rate. This leads to an improved chick quality and subsequent post-hatch performance. 

Roger Banwell, Hatchery Development Manager, Petersime nv

COa by-product of incubation?

Historically CO2 has been simply considered as a by-product during incubation and as toxic at certain stages of embryonic development. The degree of susceptibility of the embryos to harm from CO2 varies throughout the incubation period.

In multi-stage incubation, there will always be some eggs at a heightened sensitivity stage for CO2. Therefore the only safe approach is to maintain low levels of CO2 during the entire setting cycle by means of sufficient ventilation.

With the introduction of single-stage incubation and the subsequent optimisation research, the understanding of the function of the element CO2 greatly enhanced. The reasoning that CO2 is only a potentially harmful by-product that has to be kept in safe limits is no longer valid.

Look back to nature

As with all the aspects of Embryo-Response Incubation™, the best guidance is looking at the natural incubation process. The best way to look at the transportation of gas is to think in terms of partial pressure with respect to replicate the rate of exchange experienced by the developing embryo in the nest.

In a commercial incubator, the surrounding free air space and high rate of air movement can in no way represent the nest conditions. But by adjusting the partial pressures of both gaseous and fluid differentials, the optimum conditions for the developing embryo can be replicated.

COinfluences growth rate

Numerous studies have identified how variable CO2 levels during different embryonic development phases of incubation have a direct effect on chick quality and subsequent post-hatch performance. The graph below shows how a growth curve at the farm can be influenced through various CO2 levels during the embryo developmental phase.

By applying the correct level of CO2 during incubation, the post-hatch efficiency can be optimised according to the target weights. The optimum growth depends on the specific requirements of the customer.

Hatch window

The CO2 profile not only influences the growth rate of the embryo, but also the hatch window. In a multi-stage incubator, the constant need for ventilation, heating and cooling generates a wide temperature bandwidth. As a result, multi-stage incubation creates a significantly wide hatch window.

It is possible to reduce this hatch window considerably by applying adequate CO2 levels during the different phases of the hatching process. This is again inspired by the natural incubation process. The attentiveness of the parent bird during the natural hatching process can be replicated. This creates the optimum hatching conditions because the same stimuli as in the nest are present.


Single-stage incubation allows precise control of the CO2 level during incubation. This makes that CO2 becomes a tool to optimise the incubation process instead of a by-product. Applying a correct CO2 profile enhances chick quality, subsequent post-hatch performance and leads to a reduced hatch window.