Birds in the wild use their beaks to turn 3-5 time per hour. This kind of natural instinct not only enables the eggs to be turned to another angle, but also enables the eggs on the edge to be moved to the center and get even warm.
Since the egg yolk contains more fat than albumen, its specific gravity is lower than that of albumen. Therefore, the egg yolk always tends to float on the albumen. Without turning the eggs for long time, the embryo is easy to be sticked onto the shell membrane. The purpose of turning eggs is to prevent the embryo from touching the shell membrane in the same position, so as to avoid sticking; to boost embryo’s movement for better blood vessel development; to keep a proper position of yolk sac and amniotic cavity for the embryo’s better assimilation of protein. Furthermore, to turn eggs can help all the hatching eggs to get even heat. Therefore, it is essential to turn the eggs at a regular basis.
During normal incubation process, the embryo develops with its head towards the air cell. If eggs placed with the small ends up, most of the embryo’s heads
will be towards the small end. In this case, in pipping period, the poult will die because its beak cannot get into the air cell for lung breathing.
Therefore, when setting the eggs, the large end of the egg must be upwards or place the eggs horizontally. Never place the eggs with the small ends up. The egg incubator’s turning angle is about 45 degrees, and the vertically placed eggs will be horizontally placed after automatic turning. When horizontally placed, the large end of the egg is naturally higher than the small end. Since the air cell is in the large end, the poult will develop with its head towards the air cell. According to practice, it is proved that setting the eggs horizontally is much better than vertically, especially for some large size of species, such as goose, ostrich, and so on.
How many times should the eggs be turned every day?
When an automatic egg incubator is used, turn the eggs at least once every two hours. Don’t turn the eggs without any intervals, which can adversely affects the embryonic development. According to practice, the hatchability doesn't change when eggs are turned for 6-12 times, but begins to decrease when eggs are turned for less than 6 times.
Stop turning eggs 3-4 days before hatching. By this time, the poult has developed a body of feather and can turn itself, so it wont be stick with the shell membrane. Moving the eggs to the hatcher 3-4 days before hatching is better than doing this work 2-3 days before hatching, because 2 days before hatching is the key time for the poult to transfer from chorioallantois respiration to lung respiration. This time is the weakest time for the embryo and the death peak time. At this time, the embryos are very sensitive to the environmental changes and any temperature change or fierce shake will cause embryo’s death. Therefore, try not to move the egg to hatcher during this key time.
Cooling eggs is not necessary for a good incubator. This job is to dissipate the residual heat in the incubator. A good incubator can automatically adjust the temperature, and no residual heat is left in the incubation machine, so there is no need to cool the eggs. Whether it is needed to cool the eggs is determined by the way which the temperature is controlled. In the old machine, the temperature sensor was fixed in the incubator space and can measure incubator space temperature only.
In actual practice, the egg temperature is different from incubator space temperature. At the beginning of incubation, the hatching eggs don't produce heat. In order to get 38℃ for the eggs, the incubator space temperature should be set at 39 ℃. But in the late stage of incubation, when the incubator space temperature is 37℃, the egg temperature can reach above 38℃. Sometimes, the egg temperature can be much higher than 38℃ if it is not well monitored. At this time, to lower the egg temperature, the eggs must be cooled down.
When cooling eggs, first swift off the power, open the door and then use fan to lower the temperature to 35-36℃. Continue this for 3-5 hour and then again set the temperature to supply heat. If the hatching eggs overheat to a great extent, the eggs must be pulled out and even water sprayed to cool down. To cool the eggs in time can be a remedial measure.
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