Hatchability was significantly lower in the eggs incubated at high ambient temperature (38.8C)
but there was no influence of breeder age on hatchability.
Heier & Jarp reported that mean hatchability increased in eggs from breeders in their first production
cycle 28 to 36 week decreasing afterwards.
The lack of differences in hatchability observed in present study may be related to correct egg management,
the short interval between lay and incubation and eggshell quality.
Bennett reported reduced hatchability in eggs from old breeders; however, in that study the
specific gravity of about 90% of the eggs of 55 week old breeders was lower than 1.080.