الفهرس 
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Abstract
This udy was carried out at the Poultry Research Farm, Poultry Production Dept., Faculty of Agriculture, Assiut University. The experiment aimed to evaluate the effect of intermittent feeding and flashed lighting regimens and their interaction on growth performance, carcass traits, blood parameters and economic efficiency of Sasso broiler chickens The experiment followed a 2×3 factorial design: two intermittent feeding systems and three light regimens. A total number of 180were used in this experiment. Chicks were divided into 2 sections of 90 birds each received two feeding systems: ad-libtum or intermittent (IF). Each section was divided into three groups of 30 chicks each (followed three light regimens). Therefore, the experimental birds were divided into six treatments as follows: < group 1 (G1):Control group where chicks were fed ad-libtum (CF) and exposed daily to continuous light (24 CL group 2 (G2):Chicks were intermittent fed: 6h Feed+6h off (IF) and exposed daily to continuous light (24 CL group 3 (G3):Chicks were fed ad-libtum (CF) and exposed daily to 12h continuous light and 12 h flash light (12h CL:12h FL group 4 (G4):Chicks were intermittent fed: 6h Feed+6h off (IF) and exposed daily to 12h continuous light and 12 h flash light (12h CL:12h FL). group 5 (G5):Chicks were fed ad-libtum (CF) and exposed daily to 24 h flash light (24 FL group 6 (G6):Chicks were intermittent fed: 6h Feed+6h off (IF) and exposed daily to 24 h flash light (24 h FL). All chicks were randomly housed in 18 pens (6 treatments), each treatment was divided into three replicates, 10 birds each. The chicks were wing-banded, and housed in floor pens on wheat straw litter. Experimental pens were equipped with ventilation, gas heating systems and electrical heaters to provide the required temperature. The pens were light proofed by using double-layer black curtains on the windows.
The obtained results could be summarized as follows 1. Body weight (BW A.Feeding system: Significant differences (P≤0.05) were detected in BW between intermittent feeding (IF) and continuous feeding (CF) systems at 2 week of age. Birds of (IF) system had significantly (P≤0.05) higher BW than those of (CF) system B.Lighting regimen Significant differences (P≤0.05) were existed in BW between continuous and flash regimens at 2, 4 and 5 weeks of age. BW of birds exposed to flash light regimen (FL) was significantly (P≤0.05) lower than birds exposed to continuous light regimen (CL) or continuous + flash light regimen (C+FL) at 1-2 week of age. While, at 3-4 and 4-5 weeks of age, all flash light regimens (FL1 and FL2) were significantly equal in BW (P≤0.05), but significantly higher than (CL) light regimen 2. Body weight gain (BWG A.Feeding system Significant differences (P≤0.05) were found in BWG between intermittent feeding (IF) and continuous feeding (CF) systems at 2-3 week of age. Birds of (IF) system had significantly (P≤0.05) higher BWG than those of (CF) system B.Lighting regimen There were significantly (P≤0.05) differences in BWG between continuous and flash regimens at 1-2, 2-3, 3-4 and 5-6 weeks of age. At 1-2 week of age, BWG of birds exposed to flashlight regimen (FL) had a significantly (P≤0.05) lower BWG than birds exposed to continuous light regimen (CL) or continuous + flash light regimen (C+FL). While, at 2-3 week of age, birds exposed to (C+FL) regimen had significantly higher BWG (P≤0.05) than birds subjected to (CL) regimen. At 3-4 week of age, birds exposed to (CL) regimen had significantly lower BWG (P≤0.05) than birds exposed to (C+FL) or (FL) regimens. On the contrary, at 5-6 weeks of age, birds exposed to (CL) regimen had significantly higher BW (P≤0.05) than birds subjected to (C+FL) and (FL) regimens 3. Feed consumption (FC): A.Feeding system There were no significant differences between intermittent feeding (IF) and continuous feeding (CF) systems in feed consumption at all ages B.Lighting regimen: Significant differences (P≤0.05) were existed in FC between continuous and flash regimens at 1-2 and 2-3 weeks of age. At 1-2 weeks of age, birds exposed to (CL) regimen had significantly (P≤0.05) higher FC than birds subjected to (C+FL) regimen. While, birds exposed to (CL) light regimen consumed significantly (P≤0.05) more feed than those exposed to other lighting regimens at 2-3 weeks of age 4. Feed conversion ratio A.Feeding system There were no significant (P≤0.05) differences between intermittent feed (IF) and continuous feeding (CF) in feed conversion ratio at all ages B.Lighting regimen Significant differences (P≤0.05) were existed in FCR between continuous and flash regimens at 1-2 and 2-3 weeks of age. At 1-2 week of age, it was found that birds under (C+FL) regimen had significantly (P≤0.05) better cumulative feed conversion ratio than (CL) regimen. While, birds of (C+FL) or (FL) light regimens had significantly better FCR (P≤0.05) than birds subjected to (CL) regimen for the period 2-3 week of age 5. Carcass characteristics A.Feeding system There were no significant differences between (IF) and (CF) systems in all carcass traits and body organs except that of fat B.Lighting regimen There were no significant differences between continuous and flash regimens in all carcass traits and body organs.
6. Blood Parameters:
A. Feeding system:
Birds of (CF) system had significantly (P≤0.05) higher values than those of (IF) system in (albumin : globulin ratio). While, no significant differences were observed between (CF) and (IF) systems in all blood parameters.
B.Lighting regimen:
Birds exposed to continuous + flash light regimen (C+FL) had significantly (P≤0.05) lower AST than birds exposed to continuous light regimen (CL) or flash light regimen (FL). However, birds exposed to (FL) light regimen had significantly (P≤0.05) higher AST than those under other regimens. In regard to ALT, there were significantly (P≤0.05) higher values for the birds raised under (FL) than the birds raised under other light regimens.
Glucose concentration was decreased significantly (P≤0.05) in the birds raised under (CL) light regimen as compared to the birds under (C+FL) regimen. While, the birds exposed to (FL) regimen showed significantly (P≤0.05) the lowest values compared to the birds subjected to other regimens.
For cholesterol and Cholesterol : Lipids ratio, the birds exposed to (CL) regimen had significantly (P≤0.05) higher than the birds exposed to (C+FL) regimen. Corticosterone in the birds exposed to (FL) regimen significantly (P≤0.05) increased than in the birds exposed to (CL) or (C+FL) regimens. Also, the birds exposed to (C+FL) regimen showed the lowest value compared to those of the other regimens. For heterophils and (H : L ratio), the birds exposed to (FL) regimen had significantly (P≤0.05) the highest values compared to (CL) or (C+FL) regimens.
7. Meat Quality ( chemical composition and sensory traits ):
A.Feeding system:
No significant differences (P≤0.05) due to feeding system were found in meat chemical composition. However, significant differences (P≤0.05) were detected between continuous feeding (CF) and intermittent feeding (IF) systems in sensory traits: tenderness. Tenderness of the birds exposed to (IF) was significantly (P≤0.05) higher than those exposed to (CF).
B.Lighting regimen:
Meat chemical composition of the birds exposed to different light regimens were not significantly different except that of fat. Fat of the birds exposed to continuous light regimen (CL) was significantly (P≤0.05) higher than of the birds exposed to flash light regimen (FL).
For tenderness, it was significantly (P≤0.05) higher in the birds raised under (C+FL) regimen. While, the birds exposed to (FL) regimen showed significantly (P≤0.05) lower tenderness than those exposed to (CL) or (C+FL) regimens.
8. Body Measurements and Leg Problems:
A.Feeding system:
The birds received intermittent feeding (IF) had longer keel bone than the birds subjected to continuous feeding (CF).
B.Lighting regimen:
The birds raised under (C+FL) regimen had significantly (P≤0.05) longer shanks than (FL) regimen. While, body depth was significantly (P≤0.05) greater in the birds raised under (C+FL) regimen than the control birds. In regard to leg problems, the birds exposed to (FL) regimen had significantly more leg problems (P≤0.05) than the birds subjected to (C+FL) regimen.
9. Mortality rate, plumage condition and body temperature:
A.Feeding system:
Significant differences (P≤0.05) due to feeding system were found in tonic immobility log, plumage condition, body temperature and mortality rate.
B.Lighting regimen:
The birds exposed to (CL) showed significantly (P≤0.05) higher tonic immobility log than the birds exposed to (FL) regimen. While, the birds exposed to (FL) regimen had intermediate values.
10. Economic efficiency:
The highest net revenue value and the highest economic efficiency were proved for group 5 (ad-libitum feeding + continuous flash lighting) as compared with the other groups.
CONCLUSION
The results of this study suggest that intermittent feeding regimen following two cycles per day (6F:6S) and intermittent flash lighting program (12CL:12 FL) improved (feed efficiency and meat tenderness), low abdominal fat and relative high dressed carcass), low leg problems, behavioral and physiological stress indicators. In addition, the relative improve in economic efficiency without any adverse effects on studied performance or physiological parameters till marketing age of broiler chickens, while continuous feeding system and flash lighting program (24 flash) recorded the highest economic efficiency compared to the other groups.
These recommended regimen (6F:6S) and (12CL: 12 FL) seems to be more suitable for broiler strains selected for rapid growth that cannot stand intermittent nutrients supply for more than six hours. Also, such a regimen may be more practice and more acceptable in broilers farms that equipped with automatic feeding and lighting system with promising considerable saving in feed and energy (electricity) expenses.