As winter approaches, pig producers are keenly aware of the challenges of colder months to animal welfare and productivity. While temperature control often takes center stage, recent scientific papers published in 2025 are shedding new light on the critical role of lighting strategies. These studies investigate how light intensity, spectrum, and duration can be optimized to enhance pig health, behaviour, and farm efficiency.
The Nuances of Light: Intensity, Spectrum, and Photoperiod
A significant PhD thesis published in May 2025 investigated the effects of various lighting conditions on the welfare of growing-finishing pigs. The research explored various light intensities, from 45 to 968 lux, and different light spectra (colour temperatures from 2594 to 6235 K), including UVB light. Key findings from this work include:
- Light Intensity: While light intensity showed no apparent effect on pig growth or carcass abnormalities, automated video analysis revealed subtle differences in hourly activity patterns. High-intensity light was observed to reduce afternoon activity peaks, whereas medium intensity led to more pronounced peaks. This suggests that pigs can adapt to various intensities, but specific levels might subtly influence their daily routines.
- Light Spectrum: The study found inconsistent effects of light spectrum on pig behaviour and activity. However, a notable benefit of UVB light exposure was identified: it increased vitamin D levels in pigs and reduced the severity of body and ear lesions, occasionally limiting damaging behaviours. This highlights a potential avenue for improving pig health through specific light wavelengths.
Further reinforcing the importance of light, a scientific review article published in Frontiers in Animal Science emphasized the need for greater attention to the intensity and duration of light and dark exposure to ensure animal welfare in indoor housing for pigs and cattle. This review highlighted three key light parameters:
- Photoperiod (Duration): Earlier studies, as referenced in the 2025 review, indicated that the duration pigs are exposed to light significantly influences feed intake, sexual maturity, and resting behaviour and is also linked to tail biting. The research team suggested that “pigs exposed to extended lighting periods attained more welfare.
- Illumination (Intensity): Along with photoperiodicity, illumination was deemed most relevant for securing the welfare of farm ungulates.
- Colour Perception: The review noted a tendency to overestimate the importance of colour perception from a human perspective, suggesting that contrast discrimination, combined with illumination intensity and quality, is more relevant for animal orientation and interaction with their environment. The authors advocated for more preference testing studies to understand animals’ motivation for specific light conditions, which could improve welfare, health, and performance.
Another review published in PMC provided specific guidance on photoperiod management for different pig groups. It is suggested that for pigs (excluding boars), continuous light exposure exceeding 12 hours per day can enhance growth and production performance. In contrast, boars should limit daily light exposure to less than 10 hours to optimize reproductive and productive efficiency. This underscores the need for tailored lighting strategies based on the animals‘ specific physiological stage and purpose.
General Lighting Guidelines from 2025
A publication from International Laboratory Animal Day discussed pigs in biomedical research and provided general housing guidelines. It stated that pigs require lighting for at least eight hours at 80 lux or equivalent daylight.
Key Takeaways for Producers
- Focus on Duration and Intensity: Recent reviews emphasize that illumination (brightness) and photoperiod (duration) are the most relevant factors for pig welfare. More extended lighting periods may contribute to higher welfare, but specific durations should be chosen based on the animal’s purpose (e.g., >12 hours for growth, <10 hours for boars).
- Consider UVB for Health: The finding that UVB light can increase vitamin D levels and reduce lesions suggests a potential benefit for pig health, warranting further exploration in practical applications.
- Further Research is Encouraged: The scientific community continues to call for more preference testing studies to gain deeper insights into pigs’ motivations for specific light conditions, which will further refine best practices for welfare, health, and performance.
