الفهرس 
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Abstract
The present study was carried out at the Poultry Research Center, Faculty of
Agriculture, Alexandria University; during the period from April to July 2015 (the duration
of the experiment was 120 days). The experiment was planned to evaluate the effect of egg
weight in three categories and 3 local genotypes of chickens on hatch window and their
relation with chick’s growth traits.
The eggs collected from 3 genotypes (Alexandria X Alexandria, Alexandria X
Golden Montazah and Golden Montazah X Alexandria chickens) and stored for 7 days.
Before setting, the eggs of each genotype classified into three weighed groups (45-50, >50-
55 and >55g), 3 egg weight groups X 3 genotypes. At the beginning of 470h of incubation,
hatched chicks were monitored every one hour by opening the hatcher door to determine
the first hatched chick time in each weight group / genotype. This reflects the beginning of
the hatch window duration for each weight group. For all groups, the hatcher trays were
pulling after 21 days of incubation (504 hours), which was considered the end of the
hatching window period. The previous procedures were repeated in a similar manner in
four batches of eggs, with 7-day interval among them. After 21th days of incubation, the
hatched chicks were weighed and numbered.The experiment extend to 8-week of age.
Studied traits: fertility , early and late embryonic mortality, egg weight loss percentages,
hatch window duration , hatching start point, hatchability percentages , chick yield, body
temperature , body weight and gain. Moreover, correlation and regression coefficients were
estimated. The obtained results can summarized as flows:
1. Despite of the insignificant differences, the AG and GA genotypes have higher
fertility percentages more than AA genotype (95.67, 95.35 and 90.31%
respectively). Also, the small egg weight group has higher fertility percentages
more than the medium and large egg weight groups (94.10, 93.69 and 93.55%,
respectively).
2. The present results showed insignificant differences among genotypes or egg weigh
categories in respect of early and late embryonic mortality.
3. The GA eggs have significant lowest egg weight loss value than AA and AG eggs
(9.62, 10.60 and 10.65% respectively). Also, the small and medium egg weight
groups has significant higher egg weight loss value more than large egg weight
group (10.74, 10.56 and 10.19%, respectively).
4. The eggs of GA genotype have significant narrow hatch window duration than AA
and AG genotypes (19.96, 20.59 and 20.74h, respectively). The corresponding
hatching start point values were 484.04, 483.41 and 483.26h. Also, the smaller egg
weight group has significant narrow hatch window duration than the larger and
medium egg weight groups (17.94, 20.62 and 21.23h, respectively). The
corresponding hatching start point values were 486.06, 483.38 and 482.77h.
5. Despite the insignificant differences, the GA genotype has higher hatchability
percentages more than AA and AG genotypes (89.20, 83.31 and 84.22%
respectively). Also, the <50-55 and > 55 g egg weight groups (medium and larger
categories) has higher hatchability percentages more than the 45-50g egg weight
group (88.97, 87.50 and 80.25%, respectively).
6. The chicks produce from different studied egg weight categories the cloaca
temperature ranged between 39.46 and 39.68ºC, and for different hatch window
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durations were 39.39 and 39.63ºC. However, the chicks produced from AG
genotype have significant highest cloaca temperature than those produced from AA
and GA eggs (39.72, 39.51 and 39.48ºC, respectively).
7. The genotype and egg weight has significant effect on BW at hatch, whereas the
hatch window duration effect hasn’t effect in that respect. The chicks obtained from
AA and AG eggs were significantly heavier at 1-day than those obtained from GA
eggs (38.08, 38.31 and 37.29g, respectively). The chicks obtained from large eggs
significantly heaviest at 1-day (40.80g) than those obtained from other two
categories.
8. The results indicated that medium egg weight has better chick yield percentages
than smaller and bigger egg weight. The overall mean of chick yield at hatch in the
present study was 70.62 %.
9. The effect of all three main effects (genotype, egg weight and hatch window
duration) and also their interactions found to be insignificant on chicks BW at 4, 6
and 8 weeks of age. However, the genotype and egg weight significantly affect on
BW at 2 weeks of age, whereas the hatch window effect being insignificant. The
GA chicks were significantly heaviest at 2 weeks of age than AA and AG chicks
(101.02, 93.61 and 90.56g, respectively). Also, the chicks obtained from larger eggs
(> 55 g) group significantly heavier at 2 weeks (97.09g) of age than that obtained
from small (89.13g) and medium (92.89g) categories.
10. The effect of genotype, egg weight and hatch window duration and also their
interactions found to be insignificant on chicks BWG during 2-4, 6-8 and 0-8
weeks of age.
11. The genotype has highly significant effect on 0-2 weeks BWG, whereas the GA
chicks have significant higher BWG more than AA and AG chicks (63.68, 55.53
and 52.42g, respectively). Also, during 4-6 week interval the hatch window
duration has highly significant effect on BWG values, whereas the chicks obtained
from wide hatch window duration has significant higher BWG than those obtained
from narrow or medium ones (236.76, 196.50 and 205.85g, respectively).
12. Hatch window duration had significant correlation value with chick weight at hatch
(0.765), while it being insignificant with egg weight loss (-0.132) or with chick
yield (0.166).
13. Egg weight had positive significant correlation value with hatch window duration
(0.712) or with chick weight at hatch (0.855) , while it being negative insignificant
with egg weight loss (-0.223) or with chick yield at hatch (-0.178).
14. The regression coefficient value of hatch window duration on egg weight loss
(0.0096) was insignificant. However, it being significant and positive for egg
weight (0.150).
15. The most studied correlations between body weights, body gains or between both
traits at different studied ages were positive and highly significant.
16. The results showed highly significant positive regression coefficients values for
growth traits (body weight at hatch, 2, 6 and 8 weeks of age) and (body weight gain
during 4-6, 6-8 and 0-8 week’s intervals) on hatch window duration. The increase of
one unit in hatch window increase the 8-week body weight by 6.717g and 0-8 body
weight gain by 7.759g.