1. Egg structure: The egg structure is composed of seven parts: egg shell, egg membrane, air chamber, egg yolk, protein, frenulum and ovule. The unfertilized egg is called ovule, and the fertilized egg is called blastodisc. After obtaining the appropriate temperature, it develops into embryo.
2. Incubation principle: the metabolism of the embryo depends on the activity of various enzymes in the egg, and the enzyme activity is strong
It is also restricted by temperature. The optimum temperature required when the enzyme activity is strongest is the most suitable incubation temperature required by the embryo, which is the principle of the embryo.
3. Incubation period and factors affecting incubation period: incubation period: different types of poultry, the length of incubation period
Different. Generally, the larger the bird body, the longer the incubation period. The incubation period of chicken is 21 days, 28 days for duck, 31 days for goose, 18 days for pigeon and 17 days for quail. The factors affecting the incubation period are: (1) the type of eggs: the incubation period of meat type is longer than that of egg type; (2) Egg weight: the larger the eggs of the same variety, the longer the incubation period: (3) preservation time of eggs: the longer the preservation time, the longer the incubation period; (4) Temperature: the higher the application temperature, the faster the development and the shorter the incubation period; If the application temperature is low, the development will be slow and the incubation period will be long. It is not good to shorten or extend the incubation period too much. Only when the temperature is appropriate can the shell be released on time.
4. Five conditions for incubation
（1） Temperature: Temperature is an important condition for embryo development. Under special circumstances, in a short time, the embryo
It can still develop at 32 ℃ or 40 ℃. In the early stage of incubation, because the embryo is young and lacks the ability to adapt to the external temperature and regulate the body temperature, it needs a slightly higher temperature. In the late stage of development, the embryo has begun to have the ability to regulate the body temperature, and because the fat metabolism is strengthened, it produces physiological heat of human volume, so it needs a slightly lower temperature, which is the reason why the wet temperature is high before, medium and low after. For full access and full access incubation, 1-7 days is the early stage, the temperature is 38-38.5 ℃, 8-14 days is the middle stage, the temperature is 37.5-38 ℃, 15-21 days is the late stage, and the temperature is 37-37.5 ℃. If multiple batches of eggs are hatched at the same time, the temperature can be 37.8 ℃. At 21 days, the temperature (0.5 ℃) can be properly increased to facilitate the chicken to leave the party smoothly. (1) Effect of high temperature on embryo development: high temperature shortens incubation period and increases mortality. Embryos will die in 2-3 hours at 42 ℃: (2) The effect of low temperature on the development of liver fetuses: low temperature n (can prolong the incubation period and increase the mortality rate. In a low temperature below 36 ℃, after more than one day, some embryos will be stunted and die in the shell before class.
（2） Humidity: Embryo development has a wide range of adaptation to humidity, generally between 50-70%, 1-7 days
In the early stage, the relative humidity should be 60%, 8-17 days is the middle stage, the relative humidity should be 50%, 18-21 days is the late stage, and the relative humidity should be 70%. This is because amniotic fluid should be produced in the early stage, urine should be excreted in the middle stage, and it is beneficial to shell out in the later stage. When using the stove for humidification, the water pan should be covered with a layer of plastic film. According to the required humidity, a slit or hole can be opened to automatically supply moisture. (High grade) incubator has automatic humidity control function, and the water pan does not need to be covered. When chicks hatch, they should sprinkle some water on the egg surface in order to break the shell and hatch. 1. The effect of high humidity on embryo development; It affects the discharge of allantoic fluid, resulting in long hair and large belly of young chicks, which appears bulky and dull. 2. Effect of low temperature on embryo development; Too much water in the egg evaporates, resulting in short body hair.
