Embryo mortality (Death)
Unsuccessful hatches can be caused by infertile eggs embryo mortality. Each of these conditions can be diagnosed after candling and after vandling and after hatch. Examine eggs that do not hatch to estimate whether infertility or embryo death in the basis for hatch failure. Keep records of the time of embryo death; such records can suggest changes in husbandry that can increase profitability. A sample record form for hatch and fertility failures is in Appendix B.
Embryo death predominately occurs at two periods during incubation: within the first 3 days of incubation and within the last 3 days immediately before a hatch.
Early embryo death occurs during formation of embryonic organs. Of all the eggs determined to be fertile by candling at one third of incubation, 88 percent to 93 percent should continue to develop.

Possible causes of hatching problems

Observation	Possible causes
No embryonic development	Eggs stored improperly Breeders stressed Too many hens per rooster Old or unhealthy hens or males Disease
Bloodring Early dead Dead embryos, second week	Old eggs Incubation temperature too high Incubation temperature too low Incubation Humidity too high Incubation Humidity too low Electric power failure Eggs not turned Infection Poor nutrition of breeding
Air cell too small	Humidity too high
Air cell too large	Humidity too low
Chicks hatch early Dry chicks Bloody navels Chicks too small	Small eggs Temperature too high Humidity too low
Chicks hatch late	Large eggs Old eggs Temperature too low Humidity too high
Chicks dead after pipping shell	Eggs not turned first 2 weeks Thin- shelled eggs Incorrect temperature during incubation Temperature too high during incubation Humidity too high during incubation Humidity too low during incubation Infection, disease
Unhealed naval Mushy or water-logged chicks	Temperature too low during incubation Wide temperature variation in incubator Humidity too high during incubation Poor ventilation
Malformed legs and toes	Improper Temperature during incubation Improper humidity during incubation Legs also may be harmed by hatching or holding chicks on a smooth surface
Weak chicks	Temperature too high or low Old eggs Poor ventilation
Gasping chicks	Disease Bronchitis Newcastle disease
malpositions	Temperature too high during or low Turning inadequate Large end of egg not up when set Old or poorly handled eggs Poor breeder nutrition