Effect of Constant or Gradual Reducing of Light Intensity of Ambient on Performance, Carcass Characteristics and Immune Parameters in Broiler Chickens

The light intensity of saloon may affects on production, immunity and economic indices of broiler chickens production that was not enough studied. In the present study the effect of different light intensities of ambient on growth performance, carcass characteristics, blood biochemical and immune parameters as well as economic indices were studied in broiler chickens. Three hundred one-day-old Ross broiler chicks (both sexes) were randomly divided into three treatment groups having five pens as replicates (20 birds in each) in a completely randomized design. Treatments were three light intensities in rearing saloon; conventional (20 lux), low (7 lux) and decreasing (gradually from 20 to 7 lux) that discretely offered in three saloons offered from d 8 to d 42. Chickens were fed with the same starter, grower and finisher diets over the study. Feed intake and body weight gain of chickens were measured weekly. After the end of study, 10 chickens from each treatment group were slaughtered for carcass analysis and blood sampling. Results showed that feed intake, body weight gain and feed conversion ratio of chickens over the study were not affected by ambient light intensity. Carcass parts weights and relative weights of bursa of fabricius and spleen of the chickens were not significantly different among the groups. There were no significant differences in blood biochemical metabolites and hematological parameters of the chicken reared under different ambient light densities. Antibody titer against Gumboro in broiler chickens were affected by light density (p<0.05), where in low-density group it was significantly greater than the conventional group (1.74 vs 1.30 log 2). Antibody titer against Newcastle in low-density group non-significantly tended to be greater than the conventional group. The mortality percentages of broiler chickens in the conventional, decreasing and low light intensity were 1.4, 1.5 and 0.9 percent, respectively. The electricity cost for rearing the broiler chickens in low-density and decreasing groups was as 64.74 and 33.33 percent less than the conventional group. By inclusion of electricity cost, the monetary benefit of production per chicken was approximately 1% more than other groups. Generally, due to the absence of significant differences in the growth performance and carcass characteristics of chickens treated with different ambient light densities and in the other hand, lower mortality percentage and electricity cost in low-density group, using constant 7 lux light intensity for broilers saloon has an economic advantage.