Analysis of Cluster and Unrest Behaviors of Laying Hens Housed under Different Thermal Conditions and Light Wave Length

Abstract

Laying hens are affected by the intensity, wavelength, and duration of light, and the behavioral patterns of these animals are important indicators of stress. The objective of the present study was to evaluate cluster and unrest behaviors of lying hens submitted to three environments with different treatments of monochromatic lighting (blue, green, and red). For 29 weeks, 60 laying hens from the Lohmann variety were divided into three groups and monitored by surveillance cameras installed on each shed ceiling and directed to the floor. Each group was housed in a small-scale shed and maintained under a monochromatic lighting treatment. The recordings were made at two times of the day, 15 min in the morning and 15 min in the afternoon, and the videos were processed, segmented, and analyzed computationally. From the analysis of the images, the cluster and unrest indexes were calculated. The results showed the influence of lighting on these behaviors, displaying that the birds were more agitated in the treatments with shorter wavelengths. Cluster behavior was higher in birds housed under red light. There was an interaction between the lighting treatments and the thermal environment, indicating that more studies should be carried out in this area to better understand these behavioral changes.

Keywords: LED; animal welfare; comfort index; image analysis; movement analysis; precision poultry farming.

Figure 1

Experimental houses used in the study: (a) layout of the nests, feeders and drinking fountains inside the sheds; (b) external view of an sheds.

Figure 2

Luminous spectra of the lamps used in the experiment: (a) Model TKL Colors—Blue; (b) Model TKL Colors—Green; (c) Model TKL Colors—Red. (Data provided by the manufacturer).

Figure 3

Example of segmentation of an image: (a) Original cropped image; (b) segmented image.

Figure 4

THI averages calculated for each hour, during the period of the observational study.

Figure 5

Confidence intervals of the mean for the (a) unrest index and (b) cluster index verified for the blue, green, and red light treatments.

Figure 6

Average daily values for (a) unrest index and (b) cluster index, referring to samples of 15 min videos recorded and analyzed by period of the day.

Figure 7

Interaction for (a) unrest and (b) cluster behaviors in relation to comfort, according to treatment type.