الفهرس 
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Abstract
1) One hundred and tifty of eight weeks-old commercial
L.S.L. breed which were experimented on to study the effect
of different feeding systems, with different protein levels
during the growing period on the growth and the laying performance.
2) Three dietary protein levels (18, 15 and 12%) were
used in the first period from the growing phase (8-12 weeks)
and six levels (18, 16, 15, 13, 12 and 10%)were tried during
the second period (12-20 weeks).
3) At the age of 18 weeks, calcium level of laying ration
0.5%) was lJuppl1ed for balt 0 t the sUbgrouplA, to show
the effect 0 t us1ng 1&111’1re1tioD ho •• ek. prelayil’1’.
4) In the first (8-12 w.eks), the 18 protein level
is more than that ne”d for this stage ot growth and its use
means addition of ex. cost to tile ratio”, while the 12%
:,,;~.
level is too low for traaal body we1ght developaent. So, the
15% level is pointed. the optiall1 one satisfying the
needs of the birds.
5) Generally, the protein restriction during the rearing period after 8 weeks of age results in a significant decrease
of live weight at 20 weeks of age.
6) In the laying period (20-33 weeks), the 12% protein level resulted in a great difference in weight at 20 weeks
of age due to a sort of growth retardation but those light pullets were not only able to compensate their lowered weight but also showed an increased gain to the degree that it compares well with the 18% level group.
7) Feeding lower protein level developer rations, result in reduced food consumption.
8) Better u.e tor food recorded with the level. of 18,
16% or 15, 15% compared with the 18, 18%, while slight decrease in food convers!OP was recorded with 15, 13% became very clear with the 12, 1~
9) Regarding tb!l toDd consuaption allldweight gain, the 15% was sufficient to rtisfY the needs of the bird.to the 26th week. However, birds of this group consumed lesser amount of food since 18th week.
10) In the laying period; decreasing the dietary protein levels trom 18% to 16%, 1;% to 13% and 12% to 10% during the period from 12-20 weeks of age decreased the food consumption in the laying period.
13) There was no delay in the maturity when the dietary protein was lowered from 18% to ,;%, while decreasing level to 13 and 12% resulted in delayement of maturity to about 12 days. This delayement reached 25 days when the level decree to 10% level.
11) The lower levels 13 and 12% from 12-20 weeks of age retarded the liveweight gain and by turn the sexual maturity while levels lower than 12% might attect the rate ot growth as well as the tood coaauaption, a180 the sexual maturty was too late to the dtlilreetha tit is DOt ad vocated. higher production than the 18, 18% one, while the 15, 13%
group got the the same score as the 18, 16% one.
12) Very-low production (late production and fewer egg
per hen) was recorded with birds fed on the low protein levels (’12 and 10%) during the growing period.
13) The egg weight showed no significant differences between the different groups correlated with the protein regimens and there was an increase in the egg weight as the bird ages. As an average, in this experimental period of laying, the low
levels of 12, 12 and 12, ,0% groups and group IA2 of high
level produced the hignest weights. While the other levels of protein did not show signiticant differences.
14) Concerning the shell, yolk and white, the differences between the different groups, found to be nonsignificant, taking the IIA group as control.
15) Statistical 4ata for the relatiop between the level of the dietary prote~in the growing rat~ons and the percentage of each of the” components.
16) Shell thickness was not affected by increasing the
Ca level in the prelaying diet of group lAZ’
17) Feeding the pUllets a percentage ot Ca (3.5%) as in the laying ration at the 18th week ot age did not show any effect on the laying performance. In spite of the unclear effect, the group IA2 showed big sized eggs, late sexual maturity and slightly delayed egg production.
18) The lowest amount of food consumed to produce one
kg egg was recorded by group IIA, while the groups IlIA and B red the lowest protein levels required larser amounts or food, so the last two groups casted more.
19) The most eCOlllOmicgroup is that fed on 15,15% protein with an increase of 0.3 or 0.8 PT. for the 18, 18%, and 18,16% gr-oups and 0.5 and 0.11 tor the 15, 13% and 12, 12% groups for egg cost.
20) The levels of dietary protein during the growing
period does not affee~serum protein and the absorption and me taholism.