When separate hatcher is used temperature is maintained at about 98☏ and relative humidity at 70 to 80 per cent to obtain good hatch. Use of separate hatcher improves hatchability. No turning is required after 18 days of incubation. In this egg trays turn through an angle of 90°. Modem incubators are provided with devices for automatic turning of eggs at least 8 times or more during 24 hours. Eggs should be turned at least 4 times during a day when turning is done by hand. Turning or eggs in the incubator improves hatchability. Hatchability decreases when eggs are placed in the incubator with narrow end up as the embryo develops with its head in the small end. temperature requirement decreases as the humidity increases.įertile eggs are loaded into the incubator with broad end up.The relative humidity should be around 60 per cent during the first 18 days of incubation and 70 per cent in the last 3 days for optimum hatchability. In fowls egg takes about 21 days to hatch. Dry and wet bulb thermometers are used for measuring humidity. Humidity in the incubator affects hatchability. When abnormal temperature conditions extend over a long period, hatchability is adversely affected by increase in embryonic mortality and weak and deformed chicks. Low temperature slows down the development of embryo and higher than optimum temperature hastens the embryonic development. It usually varies from 99.5° to 100.5☏ (37.2☌ - 37.8☌) for forced draft-type incubators and about 1☏ higher for still-air incubators. The incubator temperature should be maintained as recommended by the manufacturer. Optimum and uniform temperature inside the incubator is very essential for obtaining satisfactory results. The physical factors necessary for successful incubation are temperature, humidity, gaseous environment and turning of eggs. Incubators, which provide similar environment as that of broody hens, but more efficiently, are used at present for hatching of eggs. This method of hatching is highly unsatisfactory for large-scale production of baby chicks. Only 10 to 12 eggs can be put under 1 hen. Desi hens proved to be ideal for this purpose. In early days eggs were hatched by placing them under broody hens. Hatching of eggs refers to the production of baby chicks.
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