الفهرس 
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Abstract
The current study was carried out at the Research Poultry Farm, Faculty of Agriculture, Assiut University, Assiut, Egypt. The aim of this study was to evaluate the effect of lighting programs and vitamin D3 levels on the performance, as well as economic efficiency of broilers under semi-intensive production.
This research was performed with two hundred and seventy broiler chicks from a common commercial strain (Sasso). The experiment was arranged in a factorial design (3*3). Three light regimes (24 hours continues light (C), 12 continues light plus 12 hours’ flash light (CF) and 24 hours’ flash light (F) and also three levels of vitamin D3 were used (control, 200 and 400 ICU/kg diets). Two hundred and seventy chicks were randomly distributed into nine treatments (30 chicks each). Each treatment includes three replicates of 10 chicks each.
They designed as follow:
1. Treatment 1 (T1): Chicks were exposed to twenty-four hours of continues light and fed a diet with level one (zero international chick unit of vitamin D3).
2. Treatment 2 (T2): Chicks were exposed to twenty-four hours of continues light and fed a diet with level two (two hundred international chick unit of vitamin D3).
3. Treatment 3 (T3): Chicks were exposed to twenty-four hours of continues light and fed a diet with level three (four hundred international chick unit of vitamin D3).
4. Treatment 4 (T4): Chicks were exposed to twelve hours continues light plus twelve hours’ flash light and fed a diet with level one (zero international chick unit of vitamin D3).
5. Treatment 5 (T5): Chicks were exposed to twelve hours continues light with twelve hours’ flash light and fed a diet with level two (two hundred international chick unit of vitamin D3).
6. Treatment 6 (T6): Chicks were exposed to twelve hours continues light with twelve hours’ flash light and fed a diet with level three (four hundred international chick unit of vitamin D3).
7. Treatment 7 (T7): Chicks were exposed to twenty-four hours of flash light and fed a diet with level one (zero international chick unit of vitamin D3).
8. Treatment 8 (T8): Chicks were exposed to twenty-four hours of flash light and fed a diet with level two (two hundred international chick unit of vitamin D3).
9. Treatment 9 (T9): Chicks were exposed to twenty-four hours of flash light and fed a diet with level three (four hundred international chick unit of vitamin D3).
The criteria studied were body weight mean, average daily weight gain, feed consumption, feed conversion ratio (feed/BWG), carcass measurements, chemical composition of broiler chicks’ meat, meat quality (sensory traits) of broiler chicks, some plasma constituents, body structure, physiological and behavioral parameters, health parameters, performance evaluation and economic efficiency during fattening period.
The obtained results could be summarized as follow:
1. Body weight (BW):
There were significant differences in body weights due to lighting programs at 3, 4, 5 and 6 weeks of age (P<0.05). The results showed insignificant differences at one day old and two weeks of age as affected by lighting programs. However, body weight of Sasso broiler chicks which exposed to a continues+flash and flash lighting program were heavier than continues lighting programs.
Regarding to the effect of vitamin D3 levels, there were significant differences on body weight at 3,4,5 and 6 weeks of age (P≤0.05). There were insignificant effects at one-day old, one week and two weeks old of age. Level 2 and level 3 of vitamin D3 supplementation groups had significantly heavier body weight than level 1.
2. Body weight gain (BWG):
There were significant differences due to lighting programs at three, six weeks of age and the mean gain (P≤0.05). There were no significant differences in body weight gain at 1, 2, 4, and 5 weeks of age due to the lighting programs. However, body weight gains of Sasso broiler chicks which exposed to the continues+flash and flash lighting programs were better than the continues lighting programs.
There were significant effects due to vitamin D3 supplementation levels at 3, 4, 5, weeks of age and the mean gain (P≤0.05). There were no significant differences at the first, second and sixth weeks of age as affected by vitamin D3 levels. However, broilers that had fed on diet with level two of vitamin D3 was significantly equaled with level three of vitamin D3 in the mean gain weeks of age, and both groups were higher than the chicks which fed on level one of vitamin D3.
3. Feed consumption (FC):
There were no significant differences due to lighting programs on feed consumption at all ages. However, feed consumption of Sasso broiler chicks which exposed to the flash lighting program were numerically lower consumption than the other both lighting programs.
Regarding with the effect of vitamin D3 levels, there were no significant differences on feed consumption at all ages. Chicks which fed on diet with vitamin D3 level 2 and 3 were numerically lower in feed consumption than the level one in the mean consumption of all weeks.
4. Feed conversion ratio (G feed/ G gain):
There were significant differences in FCR due to lighting programs at the intervals between 2-3 weeks of age, and the mean FCR (P≤0.05). However, feed conversion ratio of Sasso broiler chicks which exposed to a flash lighting and continues+flash lighting programs were better than that group raised under continues lighting program.
Regarding with the effect of vitamin D3 levels, there were significant differences on feed conversion ratio at the intervals between (2-3), (3-4), (4-5) weeks of age and the mean FCR (P≤0.05). Chicks which fed on diet with level 2 and 3 of vitamin D3 were better than level 1.
5. Carcass traits:
There were insignificant effects due to the lighting programs on carcass traits of Sasso chicks except, abdominal fat it was significant differences due to lighting program (P≤0.05) the chicks which raised under flash lighting program were the lowest percentage than other lighting groups.
Regarding with the effect of vitamin D3 levels, there were significant effects on thigh and giblets percentage (P≤0.05). However, Chicks which fed on diet with level 2 and 3 of vitamin D3 were higher than chicks which fed on diet with level 1 of vit. D3. While, Chicks which fed on diet with level 2 and 3 of vitamin D3 were lower in giblets percentage than chicks which fed on diet with level 1 of vit. D3. the rest of carcass traits had insignificant effects.
6. Liver, gizzard, heart, pancreas and gall bladder:
There was significant difference due to lighting programs in gall bladder (P≤0.05). There were insignificant effects due to the lighting programs on liver, gizzard, heart and pancreas of Sasso chicks.
There was a significant effect due to vitamin D3 levels on heart and pancreas percentage (P≤0.05). However, Chicks which fed on diet with level 2 and 3 of vitamin D3 were higher than chicks which fed on diet with level 1 of vit. D3. in heart and pancreas.
7. Lymphoid organs:
There were insignificant effects due to the lighting programs on lymphoid organs of Sasso chicks.
There was a significant effect due to vitamin D3 levels on lymphoid organs spleen, bursa and thymus at (P≤0.05). However, Chicks which fed on diet with level 2 and 3 of vitamin D3 were higher than chicks which fed on diet with level 1 of vit. D3 in spleen and thymus percentages. While, Chicks which fed on diet with level 1 and 2 of vitamin D3 were lower than chicks which fed on diet with level 3 of vit. D3 in bursa percentage.
8. Plasma protein and glucose:
It could be observed that there were significant differences in plasma glucose due to the effects of lighting programs (P≤0.05). Chicks raised under continues+flash lighting program had significantly high level of glucose than chicks raised under the other lighting programs.
No significant differences were observed for plasma protein and glucose of treated chicks by vitamin D3 levels.
9. Liver enzymes and thyroid hormones:
There were significant effects due to the lighting programs on liver enzymes and thyroid hormones of Sasso chicks. No significant differences were observed for T3/T4 ratio due to lighting program. Chicks raised under continues or flash lighting programs had significantly higher levels of AST and ALT (P≤0.05) than the other lighting program. Chicks raised under both continues+flash or flash lighting programs had significantly higher levels of T3 (P≤0.05) than the other lighting program. Chicks raised under continues+flash lighting program had significantly higher level in T4 (P≤0.05) than other lighting programs.
10. Blood total cholesterol and total lipids levels:
There were significant effects due to the lighting programs on blood cholesterol and total lipids of Sasso chicks. Chicks raised under continues or flash lighting programs had significantly higher levels of total cholesterol (P≤0.05) than the other lighting program. Chicks raised under flash lighting program had significantly higher level in total lipids (P≤0.05) than other lighting programs. Chicks raised under continues lighting program had significantly higher levels in total cholesterol/ total lipids (P≤0.05) than other lighting programs.
No significant differences were observed in total cholesterol, total lipids and cholesterol/total lipids of treated chicks by vitamin D3 levels.
11. Plasma total calcium and phosphors:
There were no significant effects on blood calcium and phosphors due to lighting programs.
There were significant effects due to vitamin D3 levels on blood calcium and phosphors of Sasso chicks. Chicks which fed on diet with level 200 ICU/Kg and 400 ICU/Kg of vitamin D3 were higher than chicks which fed on diet with level 0 ICU/Kg of vit. D3 in phosphors level (P≤0.05). Chicks which fed on diet with level 200 ICU/Kg and 400 ICU/Kg of vitamin D3 were higher than chicks which fed on diet with level 0 ICU/Kg of vit. D3 in calcium level (P≤0.05). Regarding with phosphors/calcium there were no significant effects due to vitamin D3 levels.
12. Body structure:
There were significant effects due to the lighting programs on body depth of Sasso chicks. Chicks raised under continues+flash lighting program they were higher in body depth than other lighting programs. There were insignificant effects due to the lighting programs on keel bone length and shank bone length.
No significant differences were observed for keel bone length, shank bone length and body depth of treated chicks by vitamin D3 levels.
13. Physiological parameters:
There were significant effects due to the lighting programs on physiological and behavioral parameters (body temperature and plumage conditions) of Sasso chicks. Chicks raised under continues or continues+flash lighting programs had significantly higher body temperature (P≤0.05) than other lighting program. Chicks raised under flash lighting program had significantly higher plumage conditions value (P≤0.05) than the other two lighting programs.
There were significant effects due to vitamin D3 levels on body temperature of Sasso chicks. Chicks which fed on diet with level 2 and 3 of vitamin D3 were higher than chicks fed on diet with level 1 of vit. D3 in body temperature (P≤0.05).
14. Health parameters:
There were significant effects due to the lighting programs on health parameters (leg problems and breast blisters score) of Sasso chicks. Chicks raised under continues lighting programs had higher mortality rate 8.9% than the other two lighting programs. Chicks raised under continues or flash lighting programs had significantly higher leg problems (P≤0.05) than the other lighting program. Chicks raised under flash lighting program had significantly higher breast blisters score (P≤0.05) than the other lighting programs.
Chicks fed on diet with level one (0 ICU/Kg Vit.D3) of vitamin D3 had higher mortality rate 13.3% than the other two levels (200 and 400 ICU/Kg Vit.D3). There were no significant effects due to vitamin D3 levels on leg problems and breast blisters score.
15. Performance evaluation:
There were significant effects due to the lighting programs on performance evaluation (Performance index (PI) and European production efficiency factors (EPEF)) of Sasso chicks. Chicks raised under continues+flash or flash lighting programs they were significantly better in PI and EPEF (P≤0.05) than the other lighting program.
There were significant effects due to vitamin D3 levels on performance evaluation of Sasso chicks. Chicks which fed on diet with level 200 ICU/Kg and 400 ICU/Kg of vitamin D3 had significantly better in PI and EPEF than chicks which fed on diet with level 0 ICU/Kg of vit. D3 (P≤0.05).
16. Economic efficiency (EE):
Broilers raised under continues+flash lighting program and fed on 200 ICU/Kg of vitamin D3 showed the highest economic efficiency than the other groups.
CONCL