TECHNICAL COLUMN
Ventilation in the setter
Which is the dominant element for ventilation control: CO2 or humidity? bation), embryonic growth (day 9-18 of incubation) and the hatching process (last three days of incubation) and adapt them accordingly. As a result, parameters that used to be irrelevant in multi-stage incubation because they had little or no flexibility have become highly important in single-stage incubation methods.
Ventilation by CO2 or by humidity? This leads to a number of questions regarding the management of incubation parameters. One of the most important questions is related to ventilation: if both CO2-levels and weight loss (humidity) are managed by ventilation, which of the two elements should be controlling the ventilation actuator? To answer this question, we first need to look into both parameters more closely. 1. Humidity
Single-stage versus multi-stage During the past decades, single-stage incubation has gained popularity and eventually replaced multi-stage incubation as the dominant incubation method. This is not surprising, since it brings optimal hatch results, extraordinary chick quality and significant improvements in post-hatch performance.
Roger Banwell, Hatchery Development Manager Petersime
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In multi-stage incubation, the hatchery manager has little or no control over parameters such as CO2-levels or humidity, since eggs of different flocks, sizes and development stages are all together in one incubator. With single-stage incubation, on the other hand, he can identify the parameters that influence embryonic development (first 9 days of incu-
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The humidity levels in the incubator determine the amount of weight (water) the eggs will have lost by hatch time. Losing water through the egg shell allows the embryo to build up an internal oxygen air cell that is used for the transition to lung respiration after internal pipping. It is therefore vital that the eggs have lost the correct amount of water by the internal pipping phase. For chicken eggs, the general guideline for weight loss used to be set at 11-12% of the initial weight at day 18 of incubation (in other words, by transfer to the hatcher). This implied that the majority of weight loss had to be achieved during the first 18 days in the setter. The reason for that was that humidity levels in the hatcher were relatively high, and it was not possible to fine-tune these levels unless the hatchery manager intervened manually.
