The document details the hatching process and embryonic development of chicks, specifically focusing on criteria for selecting hatching eggs such as size, shape, shell quality, and interior quality. It outlines the process of egg collection, storage conditions, fumigation, and candling to check for defects during incubation. Additionally, it describes various types of incubators and methods for sexing chicks, as well as incubation challenges and solutions.

1. HATCHING OF EGGS

2. Embryonic development of chick- preovipositional and postovipositional
development.
At the time of lay, embryo is at gastrula stage. Postovipositional
development takes 21 days for chicken egg.

3. SELECTION OF HATCHING EGGS
1) Size of eggs. It depends on breed and strain of chicken. Medium size is preferred over too
small or too large eggs, as it may create hindrance in setting incubation trays, and also do
not hatch as good. Optimum weight for chicken eggs is about 53 (50-55) grams, for duck
eggs 65-70g and for turkey eggs 80-85g.
2) Shape of eggs. Shape of hatching egg must be oval. Shape index affects hatchability.
3) Shell quality. Eggs with sound shell must be selected. Shell should be clean and thick.
Cracked eggs must be discovered by candling, and must be discarded.
4) Interior quality. Hatching eggs must have good albumen and yolk quality. Eggs with
blood
spots, meat spots and other defects must be avoided

4. CARE OF HATCHING EGGS
Collection of eggs. Gather eggs as frequently as possible, particularly at severe weather.
Three to four gatherings per day is good. Fresh eggs must be cooled below physiological
zero (20oC) as soon as possible.
Fumigation. Preincubation fumigation can be done to destroy surface microorganisms.
Cleanliness of the shell. Clean eggs hatch better than soiled eggs. Dry cleaning with a
rough cloth or sand paper may be done.

5. STORAGE OF HATCHING EGGS
Temperature: The optimum temperature for holding hatching eggs is 13 - 18o
C. Too high
or too low temperature during storage results in poor hatchability.
Humidity: The optimum humidity for storage of hatching eggs ranges from 75-80 per cent.
Handling: Hatching eggs should be held small end down and handled carefully. Hatching
eggs should not be held for more than a week
Age of eggs: Eggs held at 18o
C can be stored for one week, thereafter, hatchability declines
progressively

6. CANDLING
• Candling is a process in which eggs are kept in front of a light source to find out the
defectsin eggshell, embryonic development etc.
• Under commercial operations,candling is done when the eggs are transferred from setter
to hatcher (at 19th day for chicken eggs).
• There are two methods of candling -The fastest method involves the use of a mass candler.
An entire tray of hatching eggs may be placed on the mass candler and examined with one
observation.
• Candling with a spot candler or individual candler is a little slower, but it is more accurate.
• Candling is done in a dark room. On third day of incubation, darkening of eggs is apparent
• and the germs can be seen developing, and some trace of blood lines are also visible.
• At seventh day, movement of developing embryos is quite visible. Red spider-like radiating
lines can be seen in fertile eggs. Infertile eggs will be clear

9. Incubation period of various species of poultry

11. HATCHERY OPERATIONS FLOW CHART
Collection of hatching eggs (6 – 8 times/ day)
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Segregation of eggs not suitable for hatching
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Dry cleaning of soiled eggs only
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Receiving eggs by the hatchery from farm 2-4 times a day
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Formaldehyde fumigation at 3 X concentration
(60g KMnO4 + 120ml of HCHO for 100ft3 area) for 20 minutes in a fumigation chamber
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Transfer of eggs to setter trays
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Storing eggs for 1-7 days at 15-18oC at 75-80% R.H.
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Removal of eggs from egg store room and allow it to sweat and dry
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Setting of eggs in the incubator (hourly turning done)

12. Fumigation at 2X concentration for 20 minutes immediately after setting
fumigate the eggs in the setter at 12-96 hrs. of incubation
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Candling on 7 days of incubation - remove infertile eggs
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Candling and shifting of eggs from setter to hatcher on 18th day
of incubation keep eggs flat in hatcher.
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Taking out the hatch on 21-22 days (chicken), removal of hatchery waste and fumigation at 3X
concentration for 20 minutes and cleaning
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Grading of chicks and discard weak chicks
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Sexing of chicks
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Dispatching of chicks

13. Type of Incubators:
1. Sectional type: The sectional type incubator is usually of small capacity; from 50 - 500
eggs with a single - layer incubation.
2. Cabinet type: They are also called as forced draft incubators because the air is evenly
distributed with the help of mechanical draft (by a fan) inside the egg cabinet. The trays set
with eggs are kept one above the other so that more eggs can be incubated in a limited
space. The arrangements for temperature control, humidity and ventilation are by
thermostat, humidistat and air inlet and exhaust respectively.

14. Incubation problems and remedies:

17. Sexing of chicks:
Vent method: Squeeze the vent region of day old chicks, evert the cloaca and examine the rudimentary process.
Male chicks will have pin head size papilla in the vent.
Auto sexing: Done with the help of sex linked characters such as rapid and slow feathering and barring and
non-barring.