Tiêu đề Copy of Animal Husbandry Part-11.pdf ✅

www.iaritoppers.in Whatsapp : +91-9694095242 Page | 2 Incubation and Hatching: Principles of Incubation: Five major functions are involved in the incubation and hatching of poultry eggs. They are: 1) Temperature 2) Humidity 3) Ventilation (Oxygen and Carbon dioxide level and air velocity) 4) Position of eggs 5) Turning of eggs 1. Temperature:  Embryo starts developing when the temperature exceeds the Physiological Zero.  Physiological zero is the temperature below which embryonic growth is arrested and above which it is reinitiated.  The physiological zero for chicken eggs is about 75°F (24°C).  The optimum temperature for chicken egg in the setter (for first 18 days) ranges from 99.50 to 99.75°F and in the hatcher (last 3 days) is 98.50°F. 2. Humidity:  Humidity for the first 18 days - 55 and 60% (in setter)  For the last 3 days ranging between - 65 and 75%.  Higher humidity during hatching period is given to avoid dehydration of chicks. 3. Ventilation:  Generally the oxygen content of the air in the setter remains at about 21%.  For every 1% drop in oxygen there is 5% reduction in hatchability.  The tolerance level of CO2 for the first 4 days in the setter is 0.3%.  CO2 levels above 0.5% in the setter reduce hatchability and completely lethal at 5.0%. 4. Position of eggs:  Artificially incubating eggs should be held with their large ends up.  Under normal circumstances eggs are set with large end up for the first 18 days (in setter) and in horizontal position for the last 3 days (in hatcher). 5. Turning of eggs:  eggs to be turned at least 8 times a day.  In large commercial incubators the eggs are turned automatically each hour i.e. 24 times a day.