الفهرس 
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Abstract
A total number of 140 Brown Hi-sex at 18 weeks. of age were used during the experiment in the first laying cycle while birds were 165 during the second laying cycle In the first laying cycle, the birds were divided randomly into 20 replicate Each replicate included 7 birds and housed in wire cages. While, in the second laying cycle, the birds were divided into four groups (control and three treatments) the birds of group 1 was as control, while the birds of groups 2, 3 and 4 were fasted for 10, 12 and 15 days, respectively, and restricted photoperiod to eight hours light / day. Water was available at all times. After feed withdrawal periods the birds in the groups 2, 3 and 4 divided to three sub group the first sub group fed a crushed yellow corn, while the second sub group fed on crushed yellow corn supplemented with minerals and vitamins, the three sub group fed on layer ration. The birds in sub groups 1 and 2 given a molt diet for three weeks after fasting period then fed layer diet until the end of experimental. But the birds in sub group 3 fed layer diet after fasting period end until the end of experimental. After molt diet, the birds in groups 2, 3 and 4 received 16 h / day. The traits were studied (hen day egg production, egg weight, egg mass, feed consumption, feed conversion, egg quality traits, body weight g). The results could be summaries as fellows.
1. First lying cycle.
1. It could be noticed that the average of (HDP) increased gradually after the first month and reached to peak egg production at forth month, then slightly decreased with some fluctuations.
2. It can be concluded that, the (EW) increased by the advance of age.
3. The average of (EM) increased gradually after the first month and reached to peak (EM) at fourth month and then slightly decreased with some fluctuations.
4. The average of (FC) increased gradually after the first month and reached to the maximum amount of (FC) at 7th month. Thereafter (FC) decreased slightly until the end of the experimental with some fluctuations.
5. The value of (FCR) decreased gradually after the 1st month and recorded the best value at 11th month and then the value of feed conversion was increased slightly up to the end of this study with.
6. The average of (Y%) increased gradually after the first month and reached to the maximum at 9th month. Thereafter decreased slightly until the end of laying cycle.
7. The average of (S%) decreased gradually after the first month until the end of laying cycle.
8. The average of (A%) decreased gradually after the first month until the end of laying cycle.
9. It could be observed that, the highest value of (EYI) was recorded at the first month of laying and then the value of (EYI) decreased gradually after the first month until the end of laying cycle.
10. The highest value of Haugh units was recorded at the 3rd month while the lowest value was recorded at 2nd month
11. The average of (ESI) increased gradually after the first month and reached to the maximum at 3rd month and thereafter decreased slightly until the end of the laying cycle with some fluctuations.
12. The average of (EBS) decreased gradually after the first month until the end of the laying cycle.
13. The average of (EST) decreased gradually after the first month until the end of laying cycle.
2. Second laying cycle.
1. The birds reached to 50% egg production at 40, 48 and 55 days after onset of fasting phase with 10, 12 and 15 days of fasting, respectively.
2. The differences of (BW) between both fasting periods were highly significant (P≤0.01). The lost in body weight of layers occurred in almost linear relationship with time of fasting.
3. The highest value of (HDP) was recorded for 12 days fasting group, while the lowest value was recorded for control group. In the recovery feeding treatments the highest value was recorded for (LR) group while the lowest value was obtained for (YC) group.
4. The highest value of (EW) was recorded for the 12 days fasting group while the lowest value was recorded in the 10 days fasting group.
5. The highest value of (EM) was recorded for the 12 days fasting, followed by 10 days while the lowest value was recorded for the control group.
6. The highest value of (FC) was recorded for control group, followed by group 10 days followed by group 12 days.
7. The best value of (FCR) was recorded for 12 days fasting group, while the lowest value was obtained for the control group.
8. The highest value of (Y%) recorded for control group while the lowest value was obtained in 12 days fasting period.
9. The highest value was recorded in control group. While the lowest value was obtained in 10 days fasting period.
10. The highest value of A% was recorded for the 10 days group, while the lowest value was recorded for the control group.
11. The highest value of (EYI) was recorded in 15 days group, while the lowest value was obtained for the control group.
12. The highest value of (HU) was recorded in the control group, while the lowest value was recorded in 10 days fasting group. The (HU) increased in the control group, compared with the other treatments.
13. The (ESI) increased insignificant by 2.13, 5 and 1 for 10, 12 and 15 days respectively as compared with control. The means of egg (ESI) increased by 4 and 3 for YC and YCM respectively as compared with LR,
14. The (ESB) decreased in significant by 9.18%, 16.6% and 9.18% in 10, 12 and 15 days fasting groups, respectively, as compared with control group. The averages of (ESB) significantly increased by about 26% and 4.22% in YCM and LR groups when compared with YC group.
15. The (ST) increased in 12 days fasting group, as compared with the control, 10 and 15 days fasting groups. The means of (ST) were 390, 380 and 390 micron in YC, MYC and LR respectively.
In general:
It could be concluded that using fasting methods of force molting for 12 days recorded the best values of performance traits (hen day egg production, egg weight, egg mass feed consumption and feed conversion) and egg quality traits (shell%, albumen%, yolk%, yolk index, Haugh unit, egg shape index, egg shell breaking strength and shell thickness) compared with other fasting periods. Moreover, using force molting improved the previous measurements compared the natural molting