Four hundred eggs produced at 32 or 40 weeks of age were hatched from
each Hubberd (H) and Ross (R) strain in the same incubator. During different intervals
of hatching period, fertility% (FR) and embryonic mortality% (EM) were recorded and
hatchability% (H) was computed. After hatch, all chicks were reared under similar
management conditions. At 7 wk of age, 10 birds from each strain and at each age of
breeder were slaughtered to evaluate carcass yield traits. Economic feed efficiency%
(EFE) was calculated. Results revealed that overall means of egg weight (54.94 vs.
56.68 g), FR% (91.75 vs. 94.3%) and H% (80.65 vs. 84.6%) were higher (P<0.01) for
H than R strain. Overall mean of egg weight was higher (P breeder age (53.72 vs. 57.9 g). FR% and H% were higher (P<0.01) for eggs produced
at 32 than 40 wk (92.5 and 81.86% vs. 92.5 and 83.39%, respectively). EM% at 0-7,
18-21 and 0-21 d of incubation were higher (P<0.01) in R (5.17, 4.63 and 19.36%)
than in H (3.71,3.45 and 15.39%), respectively. EM% at 7-14 and 14-18 d as well as
total abnormality% were not affected significantly by strain. EM% at 0-7 and 0-21 d of
incubation were higher (P<0.01) for eggs produced at 32 (16.61 and 5.36%) than at
40 wk of age (18.14 and 3.53%), respectively. EM% during 7-14, 14-18 and 18-21 d
as well as total abnormality% did not differ significantly between ages. At hatch
(P<0.01), 2, 4, 6 and 7 (P<0.01) wk of age, chick weight was heavier in H than R. At
hatch (43.45 vs. 45.98 g, P<0.01), 2, 4, 6 (P<0.01) and 7 (P<0.01) wk of age, chicks
were heavier when were hatched from eggs produced at 40 than 32 wk of age.
Average total weight gain (ATG) and relative growth rate (RGR) of chicks at 0-4 wk
were not affected by strain. However, ATG at 4-7 and 0-7 wk of age as well as RGR
at 4-7 wk were higher (P<0.01) for H than R strain. ATG at 4-7 and 0-7 wk and RGR
at 4-7 wk of age were affected (P<0.01) by age of breeders. Average feed intake (AFt)
at all intervals increased in R than H strain. Feed conversion was better (P<0.05) in
chicks of H strain at all age intervals. AFI at all age intervals were higher for chicks
hatched from eggs produced at 32 than 40 wk. Values of feed conversion did not
differ significantly. Viability% at 0-4,4-7 (90.26 vs. 91.32%, P<0.01) and 0-7 wk of age
was slightly higher in H than R strain. Viability% at 0-4 wk was higher in chicks
hatched from eggs produced at 40 than 32 wk of age (90.06 vs. 90.43%). Weights of
eviscerated bird, edible giblets and dressing were heavier in chicks of H than R strain.
Their weight relative to live body weight was higher in H than R (72.28, 7.13 and
79.40%, respectively). Weight of non-edible components was not affected significantly
by strain. Their weight relative live body weight was nearly similar in H (4.52 and 6.25
%, respectively) than in R (4.88 and 6.44 %, respectively). Weight of carcass, edible
giblets and dressing as well as non-edible weight were insignificantly heavier in chicks
hatched from eggs produced at 32 than 40 wk of age. Their weight relative to live
body weight was nearly similar. From the economic point of view, it was found that
chicks of H strain hatched from eggs produced at 40 weeks of age recorded the
highest economic feed efficiency (217.24%).