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Optimize your value chain (5) – How to recognize good and bad humidity regulation in the incubator

Optimize your value chain (5) – How to recognize good and bad humidity regulation in the incubator

We explained why and when CO2 levels should be raised or lowered in article 4 of this series by Jason Cormick, hatchery specialist at Petersime. Today we describe how you can recognize signals of good and bad humidity regulation in the incubator. We will also check if your humidity management is still in great shape.

Regulating humidity is key for egg weight loss and will get you the most profitable chicks, allowing you to optimize your value chain. Losing water through the egg shell allows the embryo to build up an internal air cell that is used for the start-up of pulmonary respiration after internal pipping.

The material of the egg shell is impermeable to gases or water so that the contents do not dry out. Therefore, moisture exchange takes place through its pores. The amount of water loss – and consequently weight loss – depends on the difference of relative humidity between the inside and the outside of the egg. At the beginning of an incubation cycle, the relative humidity of the egg is 100%. The bigger the difference between the inside of the egg and its surroundings, the more moisture is lost. Therefore, high levels of humidity will limit the amount of weight loss, while low levels of humidity will enhance weight loss. Petersime’s incubators have a sealed cabinet that allows a natural build-up of the humidity. In dry climates, humidity can be increased with a water spray nozzle.

How much weight loss should be achieved and when

From set to hatch, the chick yield (the ratio of chick weight divided by egg weight) should be around 68%. The ideal weight loss profile is found in nature and follows a non-linear rise. During the first nine days, the egg should lose weight slightly. Because the mother hen sits on her eggs very often, the humidity around the eggs is quite high, resulting in low weight loss. 

After this first stage of incubation (remember that the hen leaves the nest more regularly from day 10 onwards, allowing more fresh air to surround the eggs, see “Optimize your value chain (2) – Nature’s guidance to maximizing the genetic potential of the egg”), the embryos lose weight at a higher speed, because the relative humidity around the eggs is lower, until they have reached the ideal weight loss point and are prepared to hatch.

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A non-linear weight loss concept as found in nature

Nowadays, with Embryo-Response Incubation™ technology, egg weight loss is measured continuously and humidity levels are automatically adapted accordingly by ventilating the room so the embryos develop well.

How to recognize good and bad humidity regulation in the incubator

The egg should have lost the correct amount of water by the internal pipping phase. If it has retained too much water, the embryo may be too weak to proceed to external pipping. Chicks that have not lost enough moisture have hard stomachs and sit low in the baskets. They are lethargic and unreactive.

If it has lost too much water, the embryo risks dehydration. Red hocks are often an indication that the chick did not lose enough weight during the incubation process. At the farm, these birds do not go looking for food and water.

In comparison, a bird that has achieved a good weight loss stands...

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