Small-scale poultry farmers can predict with certainty the percentage of chicks to be hatched by testing fertility for eggs against light in a cheap  and simple process.

The procedure, which is better known as candling, together with other practices, can lead to 100 per cent natural hatching just like in artificial incubation.

A farmer does not require sophisticated training or equipment, but a strong source of light and a dark room.

Edwin Mobe, a Nyamira County poultry farmer, has consistently achieved good results with candling for more than six years.

With the help of a torch, he holds an egg against the light and observes the content. The light allows for him to see ‘dirty’ strains in the clear mass of the egg.

The strains are threads of blood vessels,  sign of life. Candling is usually done about seven to eight days after incubation.

READ ALSO: Liquid paraffin helps chicks on first feeding

In dark and thick-shelled eggs, it can be challenging to identify developing embryo after the first week.

Food and Agricultural Organisation says highly enclosed chamber with only one source of light will show the embryo responding after about 30 to 40 seconds.

This also helps solve the uncertainty in shells having marks mimicking the embryo. The farmer can also roll the egg so see the spotted mass moving unlike the stationary marks.

A lamp and cardboard can also be used if a farmer does not have a torch or bulb. They will drill a hole through the cardboard, just enough to hold the egg gently, but in position. 

Candling also helps in detecting, minutely cracked shells. A cracked egg cannot hatch because of high chances of entry of air and germs.

Dead embryo eggs can also be removed early; such embryos would appear fragmented.

READ ALSO: Factors to consider in buying day-old chicks.

Hygiene is a key factor in determining the number of chicks one will get. Handling eggs with oily hands blocks air pores, which allow for ‘breathing’.

The pores are also blocked when chicken incubate dusty nests.

Some farmers assume that fine soil helps in incubation. On the contrary, ‘sinking' eggs do not allow for proportionate turning that is meant to give equal exposure to temperature.