Abstract
Background:
The preslaughter process is a critical point in implementing animal welfare principles in poultry slaughterhouses. The duration of transportation from the farm to the poultry slaughterhouse and differences in lighting in the preslaughter room can affect animal welfare.

Aim:
This study aimed to evaluate animal welfare indicators by measuring corticosterone hormone concentration, bleeding time, and carcass quality in broiler chickens considering differences in transport duration and lighting conditions in the preslaughter room.

Methods:
This study used a completely randomized design with four treatments and two replications. A total of 40 chickens were sampled. The study was conducted across four treatments: (1) transport duration from the farm to the poultry slaughterhouses ≤ 2 hours; (2) transport duration from the farm to the poultry slaughterhouses > 2 hours; (3) blue lighting; and (4) white lighting. For treatments (1) and (2), 10 chickens from different farms were used for each replicate. Treatment groups (1) and (2) received treatments (3) and (4) using blue light-emitting diode (LED) lights with an intensity of 18 lux and white LED lights with an intensity of 321 lux for 15 s. Treatment groups (3) and (4) each consisted of 5 chickens per replication exposed to blue or white light in the preslaughter room.

Results:
The average concentration of corticosterone hormone in blue and white light was 21.329 ng/mL and white light was 26.742 ng/mL. The average bleeding time under blue lighting was 187.15 s and under white lighting was 203.05 s. Blue-light lighting can maintain carcass quality by 100% compared to white-light lighting, which produces varying quality.

Conclusion:
Corticosterone hormone concentration, bleeding time, and carcass quality were influenced by lighting. The use of blue light preslaughter significantly improved the corticosterone hormone concentration, bleeding time, and carcass quality compared with white light. Overall, blue lighting resulted in better animal welfare indicators for broiler chickens in poultry slaughterhouses. Blue lighting is recommended for implementation at poultry slaughterhouses.

Key words: Animal welfare, Broiler chickens, Lighting differences, Transport duration