Humidity: The embryos can adjust to humidity more widely. In the front period, the humidity in egg incubator can be 50%-70%. In the middle period, the humidity can be 50%. In the back period, the humidity can be 70%. The humidity condition in hatching machine can benefit the hatching, for in the front period, the hatching egg need produce amniotic fluid, in middle period, they need to produce stale, and in the back period, they are dig shell. Higher temperature can infect the growth of embryos and infect the release of the stale to result in big belly, long little feather. The lower temperature in egg incubator can cause more water in body and short little feather.