Poultry industry has to play a considerable role in the livestock subsector in regard with the provision of meat in Pakistan. As the broiler industry is increasing day by day, the factors hindering the growth rate are also being taken into account by the farmers as well as the scientists. Besides different diseases, poor management is one of the main problems which jeopardizes the poultry production. Numerous studies conducted in various countries showed that among the other managemental problems the different light regimes to which the brioler are exposed during rearing had a significant effects on the weight gained, feed consumption and FCR. The birds exposed to the intermittent light system also showed better response in connection with physical abnormalities.

The present study was conducted to observed the effect of intermittent light regimes on the development of physical abnormalities and performance of the chicks viz, feed consumption, weight gain, FCR and dressing percentage as compared with continuous light system.

In this study, three groups of 60 chicks each were subjected to light treatment from the start of 3rd week to the end of 6th week in following way:

Group A : Continuous light (control) 24 hours

Group B : 1 hr. light : 2 hr darkness

Group C : 1 hr. light : 3 hr drakness

The feed consumption, weight gained and FCR of each group were calculated at the end of 6th week age group and analysed by one way analysis of variance techniques. Least significant difference test was applied to compare the treatment means of the groups.
Beside above dressing percentage, weight of giblets, physical abnormalities and mortality in each group was also recorded.

This study concluded that the performance of broiler chicks under intermittent system of light was significantly better as compared to continuous light system. The average weight gained during treatment period in group A, B and c were 1410, 1460, and 1510 gm respectively. Similarly the FCR of group A, B and C was 1.90, 1.80 and 1.74 respectively. It is evident from the results that overall performance of birds under group C viz. 1L:3D was significantly better than either continuous light or 1L:2D system. This better performance by the group given 1L:3D light treatment may be due to a longer resting period during which the birds mainly remained inactive. The energy thus saved was converted in to growth. As the difference in feed consumption of the groups provided 1L:2D and that provided 1L:3D was non significant therefore the FCR of group given lL:3D treatment was better. The average feed consumption by the chicks in group A, B and C are 2.371, 2.329 and 2.344 Kg respectively. The feed consumption by the chicks under intermittent light system was less than continuous light but not significant.

The dressing percentage and carcass quality of the birds subject to light treatment were also comparatively better than continuous light programme.