This experiment was conducted to study the performance of Gimmizah (G)
and Golden Montazah (GM) hens which were induced to molt by fast where feed was
withdrawn until a target body weight loss of 33.04% was reached (14 days) or fed on
ration that contained high level of zinc oxide (ZO) (20,000 ppm) for 7 days. The hens
were subjected to two light length treatments, the first receiving 14 hr of light per day
(UD) throughout the 24·week experiment and the second restricted to 8 hr UD during
the dietary treatments. This group of hens received a 24-hr photoperiod for 1 wk to
provide maximum stimulation prior to initiation of dietary treatments and 8 hr UD
during the dietary treatments. Lightning interval was maintained through day 42, after
which, lightning period was increased by one-halt hr per day until it reached 14 hr UD.
Control group was maintained. All groups received a 16.84% protein layer ration
throughout the experiment and given feed and water ad libitum. Body weight loss of G
hens was significantly (P<0.01) higher than that ofGM ones at 63 weeks of age. The
fast hens and the hens treated with ZO achieved about 33% and 20% BW loss,
respectively, tilt Day 14 from the beginning of treatment. The BW of the two treated
groups was significantly less than the control one during postmolting period. The
lightining period had no effect on BW at all ages studied. In addition, G hens produced
significantly more eggs than GM ones during 72·76 weeks of age only. Both the ZO
and control groups produced approximately similar EN and they surpassed the fast
one during molting while the two treated groups produced significantly (P<0.001) more
eggs than the control one during both the 64·68,68-72 weeks of age. Moreover, Hens
on the 8 hr UD produced significantly less EN during 68-72 weeks of age than hens
which received 14 hr UD. On the other hand, the G hens had better (P<0.05) value of
FE during 68·72 weeks of age than GM ones. Moreover, the fast group had the
poorest value of FE during molting period and the feeding treatment had highly
significant effect on FE during 68-72 weeks of age only. The UD had no effect on FE.
Moreover, G hens produced significantly (P eggs produced by control hens were heavier than those of the treated hens. The
lighting period had no significant effect on EW. Moreover, light per day significantly
affected both Hu and SHT where 8 hr UD decreased Hu value but increased SHT.
Age of hens showed highly significant effect on both EWand SHT. In addition, neither
strain nor feed treatment had significant effects on For H. While UD showed no effect
on H, the F of eggs produced from hens received 14 hr UD was higher than the
restricted UD group. However, induced molting using the feeding and lighting
progr-"ns in G and GM hens realizes positive REE except that in G ones which the
REE of hens bred on 8 nr UD and fed ZO was less c:ompared with the control group.
However, it could be concluded that most of the trajts studied were improved due to
feeding and lighting programs used in this experiment.