Multistage incubation – selecting optimum settings
Written by Maciej Kolańczyk, Senior Hatchery Specialist
On the face of it, multistage incubation is an easy procedure. The setter is loaded with a new batch of eggs as the oldest batch in the setter reaches the point of needing to be transferred. A fully loaded machine contains eggs at all stages of incubation, and the average incubation age will be about 9 days. At this stage in a single-stage incubation programme, the eggs do not produce a lot of heat and their oxygen demand is limited.
Multistage incubation does not present great technological challenges. The setter can work at constant, fixed settings, aiming to create acceptable conditions for all batches. The trouble is that this 'average load' consists of batches that are in very different phases of incubation: from eggs that have just been loaded to eggs about to be transferred. The average set points might be close to the optimum for the middle groups, but they will be far from optimum for the extremes. And it is the extremes that determine the results. Too low a temperature at the beginning will cause an increase in early embryonic death. Overheating during the last days will lead to late mortality and poor chicken quality.
The eggs themselves offer a solution, however. Their opposing requirements can be utilised for mutual benefit. Fresh eggs are cool when loaded and need to be heated. Eggs containing advanced embryos must be cooled. Placing these two groups next to each other creates an opportunity for mutual heat exchange.
Although all incubator manufacturers claim that their machines create a very uniform environment, breaking the laws of physics is not that easy. Differences in air speed, distance to the coolers, heaters, humidifiers and air inlets matter, and are reflected in egg shell temperature. Cooler and warmer zones can be defined in all types of equipment, and this can be made use...
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