Candle the eggs on Day 7 and Day 14 to identify infertile and spoiled eggs.
Remove all the infertile and spoiled eggs from the incubation chamber.
After 7 days infertile eggs are still safe to eat, but spoiled eggs should be
discarded. After 14 days, spoiled eggs need to be discarded.
Some 75-90 per cent of eggs from a good breeding flock should be fertile.