Probable Cause Corrective Measures Low incubation humidity (especially during hatching) Increase incubation humidity by increasing water evaporation. Embryos dried too much. Excessive ventilation rate Reduce ventilation rate but maintain minimum air exchange to prevent suffocation of embryos.

Hatching Problems

A good hatch from a small incubator is indicated when 70 percent or more of the eggs hatch, and the chicks are active and fluffy. It is not unusual for inexperienced incubator operators to encounter problems.

One way to follow the progress of incubation is to candle the eggs. An egg candler can be purchased, or a flashlight can be used. Hold a small flashlight against an egg in a dark room to candle an egg. Part of the inside then becomes visible. By 5 days of incubation, blood vessels should be visible if the egg has a white shell. If the egg has a brown shell, several more days of incubation may be required before blood vessels are visible. If development does not occur, the eggs may not be fertile, or there may be serious incubation problems. By day 8 or 9, the chick may be startled by the light, and its movement can be seen. Candling at later stages of incubation should show that the embryo is growing and filling up the space inside the egg.

If there are problems with incubation, the chicks that hatch may provide clues about the problem. A list of possible problems and suggested solutions is given in Table 4. Chicks that have not hatched on time may be helped. If the shell is pipped (chick has punched a hole from the inside) and there is movement, the egg may be examined. The shell can be removed in small pieces. If bleeding occurs, the chick is not ready. If no bleeding occurs, the chick can be helped from its shell.

Additional information may be collected by breaking the eggs that did not hatch. If they are broken onto a flat surface, the contents will indicate an infertile egg or show how far development proceeded before death.