Enlightened pigs: Throwing light on pig welfare

Samenvatting (Engelstalig)

This PhD thesis explored how lighting conditions, especially light intensity, light spectrum, and UVB light, affects the welfare of growing-finishing pigs. Current light regulations for pig housing impose minimum thresholds for daily light duration and light intensity, despite limited scientific evidence backing existing standards. The limited literature suggests pigs respond to different light durations, intensities and spectra, however, findings are often inconsistent. Effects on pig behaviour, health, and growth were assessed in experiments testing different light intensities, spectra, and UVB exposure, using mainly LED lighting. Although no consistent welfare improvements or effects on growth were found across treatments, UVB light enhanced vitamin D levels and reduced certain skin lesions. Furthermore, a computer vision tool revealed subtle changes in activity under higher light intensities. This thesis showed that some specific aspects of pig welfare were influenced by light, and highlights the need for more pig-centric lighting concepts.