The average estimated hatchability at 25
wk of age was 66%; it increased to 86% between 31 and
36 wk and decreased to 50% at 65 wk of age. On average,
an extra day of storage until d 7 reduced hatchability
by 0.2% and from d 7 to 14 by 0.5%. Eggs from older
flocks were less sensitive to prolonged storage, whereas
they were more sensitive to season. Hatchability was
greater during late summer than during spring. The
average estimated differences in hatchability among
strains and feed companies of the breeder farms were 8
and 2%, respectively.