CHICKEN HATCHERY EQUIPMENT

Fertility and Candling

Fertility is rarely 100%. When the flock is of good producing age and the right proportion of males to hens are penned together, it can be assumed that a fair amount of eggs will be fertile. Fertility may vary from 55% to 95% with season, condition and type of birds. A good average expectancy may be that 50% to 75% of the eggs will hatch.


Fertility of eggs cannot be determined before incubating them. After 2 to 3 days, white shelled eggs may be candled to see if embryos have developed. Cracked or damaged eggs do not hatch and often develop odors and should be removed when detected.


Uniformly colored or white shelled eggs may be candled by placing a light bulb under a box or can. A hole must be slightly smaller in diameter than the egg through which light will pass. Place the egg over the hole, if a cloudy spot or mass is observed, this can be assumed to be a growing embryo. If the contents of the egg allows light to pass uniformly through it, it can be assumed that the egg is infertile.