Pigs show a preference for developing certain behaviors under specific light spectrums. Additionally, adding UVB light to the spectrum could improve pigs’ vitamin D levels. Despite its potential, there are still gaps in understanding the overall effects of the light spectrum on pig behavior, health and growth due to the limited number of studies.
Aim: Therefore, this study investigated how various light spectrums, including UVB light exposure, influence the behavior, health and growth of finishing pigs.
Methods: An experiment was carried out with a split block design on a commercial farm, in which four different light spectra were evaluated in the blocks (warm white; 2594 K, natural white; 4336 K, cool white; 6235 K, fluorescent tubes; 3787 K) and the addition of UVB light in subblocks (UVB or no UVB). Each light spectrum was tested on 112 pigs divided into two batches of eight pens each. Within each light spectrum, 28 pigs received additional UVB light. The pigs’ behavior was analyzed every two weeks, both manually and using computer vision, while their health status was assessed weekly. Pigs were weighed at the beginning of the experiment and before transport to the slaughterhouse. During slaughter, carcass abnormalities were scored and blood samples were taken to analyze vitamin D and variables related to bone growth.
Results: The effects of the light spectrum on positive and negative social interactions, exploration, and play behavior were inconsistent over time and were primarily observed during the first six weeks. Furthermore, the light spectrum had a variable impact on the activity of the pigs, depending on the week. Beginning at week 6, pigs exposed to fluorescent tubes and natural white light spent more time in active postures (i.e., standing and sitting) than those exposed to other light spectrums. However, the light spectra had no effect on the distance traveled by the pigs. The additional UVB light reduced harmful behaviors at week 4 and reduced the severity of lesions on the ears and midsection of the body throughout the growing phase. Furthermore, pigs exposed to UVB light had a higher blood vitamin D level than pigs not exposed to UVB light, which, however, had no effect on bone formation variables. None of the light treatments influenced carcass abnormalities or growth.
Conclusion: Overall, the results suggest that the light spectrum appears to have limited effects on the behavior, health and growth of finishing pigs raised under commercial conditions with limited space and a relatively unenriched environment. As this is the first study to address the effects of the light spectrum on different aspects of pig welfare, further research is needed to corroborate these findings.
Alice J. Scallerez, Sophie E Van Niefmarnges – the King, Rick PPJ of the Toll, Sabine K. Schnable, Eddie AM Buckle, Effect or light spectrum, health and growth, healed Animal Behaviour Science, Peace Animal Behaviour Science, 2025, 106711, ISSN 0168-1591,
