الفهرس 
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Abstract
This study was Carried out at the Poultry research farm of the
Department of animal production, Faculty of Agriculture •CairoUniversity
with cooperation of the Department of Animal and Poultry production ,
Faculty of Agriculture at Moshtohor,ZagazigUniversity •Benha Branch.
It was intended to study the nature of growth and to estimate the
genetic and .non-genetic Variances. heritabilities as well as genetic,
phenotypic and environmental Correlationsfor traits of body weight from
one day old up to 24 week of age on each sex of pure bred white Pekin
ducks produced from two Series of mating system in three genrations .
The adjusted data within each generation were statistically analysed
by the application of Factorial design with unequal number of subclasses
described by Becker (1975). Results obtained in body weight. absolute,
relative gain and accumlative increase in body weight at different ages Can
be summarized as follows:
1. The nature of growth of this flock could be Classified into three
stages. The first stage was characterized by rapid growth during the
period from one -day old up the age of eight weeks. Eachof absolute
and relative gain from one- day to 2 weeks of age were 100.0 grams
and 112 ” .while from 6-8 weeks of age they were 180.0 grams and
36”; respectively. In addition body weght at 8 weeks of age was
about 17 times that of one-day old.
The second stage of growth from 8-14 weeks of age, was
characterized by nearly absolute gain (about 200 grams. ) in body
weight during each period of 8-10, 10-12 and 12-14 weeks of age
with respective relative gains of 29.3’ 25. 3’ and 18. 1,. The
accumalative increases in body weight at 10 and 14 weeks of age
were about 22 and 34 times that of one day old; respectively.
The third stage was during the period from 16-24 weeks of age
which was Characterized by a grad ute decrease in absolute and
relative gain which reached 100.0 grams and 9’ during the period of
14-16 weeks of age and decreased till it reached about 33.0 grams
and 2’ during the period of 22-24 weeks of age. In addition body
weight at 16 and 24 weeks of age were about 36 and 39 times that of
one-day old; respectively.
2. Males were significantly heavier in their body weight than females at
all ages. The absolute gain in body weight for males versus females
during the period of one- day old to 2 weeks, 6-8 weeks and 12-14
weeks of age were 90 V.S.78, 196 V.S. 140 and 228 vs. 169 grams;
respectively, and the respective relative gains were 114’ V.s. 104.
7’, 40. 3’ V.S. 35.3’ and 20. 6’ V.S. 18.0’ . While the accmulative
increases were 3.5 V.S. 3.2, 16.4V.S> 13.0 and 34. 3.V.s.28.7 times
that of one-day old; respectively.
3. The obtained results shoved that generation had a highly significant
effect on body weight at all age. The F3 progeny were heavier than
each of Fland F2 Progeny. The respective absolute gain during the
periods of one-day old to 2 weeks. 6 to 8 weeks and 12 to 14 weeks
of age for FI Versus F’2VersusF3 were 52 V.S.90 V.S. 156. 144 V.S.
144 V.S.250 and 196 V.S.189 V.S.211 grams. While the respective
relative gains were (84.114 and 139\). (43. 34 and 36\) and (23.19
andI5\). Meanwhile the accumulative increases were (2.3. 3.6 and
5.5 ). 00.8.14.6 and24) and (26. 32 and 44) times that of one-day
body weight; respectively.
4. The results indicated that there were no significant difference
between sires and between group of dams for body weight or males.
females and males + females at most ages within each generation .
Also • the sire X group of dams interactions were not statistically
significantwhich means that the non-additive genetic component was
not or significant effect on body weight . therfore • the sire and the
dams were • more or less . geneticlly homozygous and therefore.
inhereted their progeny almost similar genetic make up for body
weight within each generation.
5. The respective 62
5 and 62d (over all ages) in male progeny were
relatively higher 03.05 \ and 11.38\). than those in female progeny
(9.85\ and 8.61\ ) . In addition sires contributed by about 14.65 \ j
and 9.78 \ while dams contributed by aboutl2.77\ and 10.55\ or \
the total variance of body weight of male progeny during the firstl4 -\
weeks and during the period from 16-24 weeks of age •respectively ·1
The respective estimates on female progeny were 9.92 I and 9.721
for sires and 7.58 I and 10.76 I for dams.
6. Maternal effect on male and female progeny was of negligable values
However, sex linkage effect was relatively higher during the first 14
weeks of age in both sexes.
7. Heritability estimates of h2s m h2d and h2s+din male progeny (over
all ages) overagedOA74 . 00434 and 00459 , respectively. while the
respective overages in females were 0.343 , 0.317 and 0.346 . The
results reveald that the heritability estimates were relatively higher
in male than those estimated in female progeny at a relatively earlier
ages . Meanwhile the estimates of h2s in males and females were
relatively higher than those of h2d and the estinaltes of b2s+dwere in
between.
In addition the estimates of h2s . h2d andb2s+din male versus female
progeny during the first 14 weeks of age averaged 0.536 • 0.319 and
00448 V.S. 0.266 • 0.500 and 0.313 , respectively. However. the
respective values during the period16-24 weeks or age overaged
0.380 ,0.389 and 00432 V.S. 00475. 00406 and 00410 . Tbus • body
weigbt in males is controlled additively more than in females • and
tberefore , males migbt be efficiently respond to selection than
females.
8. The genetic and the phenotypic correlations coefficients in adjested
sex based on full-sibs among traits of body weight at different ages
were possitively low in most cases . while the enviromental
correlations were relatively positively high .