The Effect of Blue-green Light on Behavioral Repertoire and Fear Responses in Broiler Chickens

The broiler chicken industry has increased the number of birds produced each year, making the mitigation of stressors that affect broiler health and meat quality increasingly important. New management strategies, like lighting protocols, could help combat stressors and promote behavioral indicators of positive welfare. This study compared the effects of blue-green and white light on broiler fear response using a tonic immobility test and behavioral repertoire in the home pen using continuous focal sampling. Day-of-hatch male broiler chicks (N=600) were randomly divided into 12 pens (n=50 chicks/pen). The pens had either a white LED light (control, n=6) or a blue-green spectrum LED light (treatment, n=6). After 12 days, 3 birds per chamber were tested for tonic immobility (TI), which involved placing the birds backwards on a V-shaped cradle for a maximum of 300 seconds, and the latency for the bird to right itself (seconds) was recorded. On day 13, the behavior of one chick per room (n=12) was observed for 9 behaviors (walk, stand, run, peck, preen, stretch, sit, drink, and eat) for 30 minutes in the morning (0930) and in the afternoon (1400). Behavior was observed using continuous focal sampling, and the duration of each behavior bout was recorded manually and using Noldus Observer XT 14 software. The results for TI revealed that there was no significant light effect on chicken latency to the right, but there was a numerical one, with birds from the control taking 137 seconds to the right compared to 115 seconds for the treatment. Lighting treatment had few significant effects on the percentage a bird spent in each behavior. Time of day had a greater influence on behavior, with birds spending a greater percentage of time drinking in the morning (p=0.02) and pecking in the afternoon (p< 0.0001). The interaction between light and time of day was significant for pecking behavior, with control birds pecking the lowest percentage of time in the morning (p=0.02) compared to both treatments in the afternoon. There were no significant 2differences observed for all other behaviors for time of day, lighting treatment, or the interaction between the two. Overall, lighting treatment had minimal impact on broiler behavior and fear, but this could largely be due to the small sample size used in the study. Future research should be done using a larger sample size to get more comprehensive results.