Influence of different Lighting Programs on Growth and Immunity indices in Broilers

This experiment subjected to investigate the effect of different light programs on growth performance, the immune system and internal organs of the broiler chicks. A total of 300 one day-old male broiler chicks (Ross-308) were randomly distributed between three treatments with a similar average weight. Each group was housed in the separated room with five pen and 20-birds per pen.The management conditions were similar for all treatments throughout the experimental period except lighting programs which from 8 to the 42 day were provided as follow: 1) 23 h light (L): 1 h dark (23L:1D), 2) 16 h L: 8 h D (18L:6D) and 3) 12 h L: 12 h D (12L:12D). At 35day-old, 0.2 mL of SRBC was injected intravenously into the chicks and at the 42 day-old, 4 chicks were randomly selected from each replicate. Anti-SRBC antibody titers were determined using a heamagglutination technique. Then Chicks were slaughtered and their bursa of fabricus, spleens, liver, heart, crops, gizzard and jejunum weighted and alsolength of jejunum were measured. The Anti-SRBC titer was the lowest with 23L:1D and the highest in the birds of 12L:12D treatments respectively (p < 0.01). The lowest weights of internal organelles were in 23L:1D and the highest in 12L:12D treatments.The  weight gain and feed conversion ratio between the treatments was significantly different in all the periods and improved with more dark hours (p < 0.05). It is concluded that lighting program with long darkness improved growth and immune indices in broilers.