te
ec
pr ot
71
45°
100
rig
Horizontal position The trays are sometimes positioned horizontally from day 14-15 of setting. Changing the position is thought to result in better air and heat distribution because it allows more air to flow faster between the setter trays. But this is only tackling symptoms. Find a solution for the root cause: the incubator should function 100% correctly!
Positioning trays horizontally creates an unrestricted flow of air through the trolleys. However, the airflow between the eggs might actually be less, which can lead to insufficient airflow at egg level. Insufficient contact of air with the egg mass will remove less heat (even if the sensor reading indicates otherwise). Check the eggshell temperature regularly.
ht
The most widely used system in Europe is setters with trolleys that can roll in and out (drive-in). The trolleys are connected to the automatic turner in the setter. Each type of setter has its own turner drive system. The eggs are always turned through an angle of 75-90°, usually hourly, and sometimes, 4 times an hour. Exchange of fluids between the various compartments, which are enclosed in embryonic membranes, is essential for good development. Turning ensures this continuous ‘decanting’. Transfer of water from the albumen to the yolk, through the embryo, starts as soon as the incubation temperature is reached and embryonic development continues. The water reaches the sub-embryonic compartment and its maximum level occurs on days 6-7. The egg content is now watery with an embryo floating on the very fluid yolk. After this, the water is distributed between the amnion (enclosing the amniotic cavity) and the allantois. Turning is essential from days 3-7. Not turning during this period will cause very limited embryonic growth and often a high mortality rate between 12-14 days. The eggs should be turned up to at least day 12, and preferably until day 15. Usually turning continues until transfer from setter to incubator on day 18.
d
Egg turning during setting
co
py
71
Positioning the eggs at an angle automatically reduces the space between them, which in turn can inhibit the airflow. With a bit of mathematics (Pythagoras) you can calculate that at an angle of 45°, the space is reduced to 71% of the distance in horizontal position.
80-90°
40-45° 40-45°
Trays positioned horizontally from day 14-15, to create an undisturbed airflow. This is absolutely unnecessary if temperature distribution in the machine is good.
7. S et t i n g
Turning through 90° in the machine, means that the eggs tilt from 45° to the left on the length axis to 45° to the right, because rotating them completely - as a hen would - is very difficult.
107
