اثر برنامه نوري متناوب و شدت نور بر عملكرد و بروز ناهنجاريهاي پا در جوجه هاي گوشتي

Effect of intermittent lighting and light intensity on the performance and leg disorders in broiler chickens

The purpose of the present study was to investigate the practical applications of alternative lighting programs as intermittent lighting at high or low intensities on the incidence of leg disorders and performance of broiler chickens. Eight hundred and sixty four day-old male and female broiler chicks (Ross breed) were randomly placed in 24 floor pens, sex separately (12 pens per sex, 36 chicks per pen). En the first 2 days of the trail, all chicks were subjected to continuous lighting [23h light (L):1 h dark (D), CL] at a light intensity of 20 lux at bird height. After 2 days, chickens were subjected to an intermittent [1h light (L):3h dark (D), EL] or continuous [23h light (L):1h dark (D), CL] lighting programs combined with two different light intensities (high or 30 lux versus low or 8 lux). According to the obtained results, birds reared at EL showed significantly higher final body weight than their CL counterparts (P<0.05). Sex differences in final body weight were observed so that males were heavier than females (P<0.05). Lighting programs or light intensities did not significantly affect cumulative feed intake whereas they had significant impact on FCR. The results showed a significant reduction in FCR for broiler reared under EL and low light intensity (P<0.05). The intermittent lighting schedule significantly (P<0.05) reduced abdominal fat deposition of both male and female broilers but light intensity programs did not significantly affect abdominal fat pad content. Effects of lighting programs or light intensity schedules on mortality and bone ash percentage were not statistically significant. Intermittent lighting combined with low light intensity program, in addition of enhanced production efficiency and lowering the cost of electricity, resulted in lower room temperature. From the practical point of view, this may be used as an efficient management technique for raising broiler during hot season in tropical and subtropical regions.