Effects of abrupt and gradual light/dark switching on growth performance, behavior, villus development, meat characteristics, and immunity of broilers.

The aim of this study is to determine the effect of abrupt and gradual light/dark switching on growth performance, behavior, villus development, meat characteristics, and immunity of broilers. A total of 270 daily male broiler chicks were used in the experiment. The study comprised three groups based on whether the transitions between light and dark periods were abrupt or gradual. No significant differences were observed among the examined groups in terms of body weight, weight gain, mortality rate, feeding, pecking, relaxing, and feather preening behaviors, carcass, and breast meat quality characteristics. Total body weight gain, total feed consumption, total feed utilization ratio, and mortality rates of broilers during the 6-week fattening period did not differ compared to the abrupt transition. Broilers in the group with gradual transition exhibited less movement, more sitting, and sleeping behaviors. It was determined that the IgG was higher in the gradual transition group. The transitions between light and dark periods influenced the characteristics of thigh meat. Villus height and crypt depth were higher in the group where a 1-h gradual transition was applied. As a conclusion, gradual transition is more appropriate in broiler rearing.