The current study investigated the effect of selection for increased egg
number during the 1st 90 days of laying on egg quality traits over four generations in
Benha chickens. A total of 18 cockerels and 180 pullets were selected according to their
BLUP values for egg number at the first 90 days of laying from Benha base population
(control). Data of 4242 eggs produced by 756 pedigreed hens fathered by 69 sires and
mothered 484 dams from four generations (base and three selected generations) were
used to estimate heritability, genetic and phenotypic correlations for egg quality traits
(Egg weight (EW), Albumen weight (AW),Yolk weight (YW), Shell weight (SW),
Haugh unit (HU), Egg shape index (ESI), Albumen index (AI), Yolk index (YI) and
Egg shell thickness (EST)). The selection effects, correlated responses and the genetic
and phenotypic trends for egg quality traits across generations were quantified or
clarified applying the updated approach of the animal model program of BLUPF90.
Heritability estimates were moderate or low for all traits (h2
= 0.05 to 0.47). Also,
genetic correlations for EW was closely positively genetically correlated with AW, YW,
SW, with magnitudes of 0.99, 0.57, 0.69, respectively. The three selected generations
were superior (P |
