Light is much more than just barn lighting — it is a biological signal in cattle housing that influences metabolism, reproduction, and behavior.
Research shows that adjusting light intensity, spectrum, and duration can boost milk yield, accelerate growth, and reduce stress in both dairy and beef systems. Yet, lighting remains one of the most under-managed factors in livestock environments. By understanding how light influences circadian rhythms and hormonal balance, farmers and technicians can access hidden gains in productivity and animal welfare. In this article we explore the science, practical applications, and future innovations of light management in cattle production.
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Light acts as a powerful biological regulator in cattle. The daily light–dark cycle, known as the photoperiod, regulates circadian rhythms, hormonal secretion, and key biological processes such as growth, reproduction, and lactation. The central pathway begins with the pineal gland, which produces the hormone melatonin during darkness. When exposed to light, melatonin secretion is suppressed, shifting downstream metabolic and hormonal activity. One of the key mediators is insulin-like growth factor 1 (IGF-1), which rises under extended light conditions and is directly linked to increased milk yield, faster growth, and improved feed efficiency (Dahl et al., 2000).
This light-driven modulation is also linked to the regulation of circadian rhythms — the internal 24-hour biological clocks that coordinate activity, metabolism, and immunity in animals. Disruptions to these rhythms, whether from poorly timed lighting or constant illumination, can impair productivity and elevate stress levels. Conversely, well-managed lighting aligns physiology with predictable patterns of feeding, rumination, and rest, reducing stress and promoting efficiency (Adamczyk et al., 2024).
Recent research has also highlighted that not only duration but also intensity and spectrum of light has an influence. Dairy cows exposed to ~150 lux respond more strongly to photoperiod extension than those under dim conditions, and certain wavelengths (e.g., blue-enriched light) may further influence alertness and activity (Lim et al., 2021; Lindkvist et al., 2023). This demonstrates that light may act as a subtle factor influencing health, behavior, and performance.
While the physiological effects of light are universal, the optimal photoperiod depends on production stage, and natural day length often does not align with cattle needs. In the Northern Hemisphere, daylight at mid-latitudes (~40–50°N) ranges from only 8–9 hours in winter to 15–16 hours in summer. This natural swing coincidentally matches two widely used management strategies: long-day photoperiods that benefit lactating cows in summer, and short-day photoperiods that are optimal for dry cows in winter. However, because production systems require year-round consistency, artificial lighting is often needed to deliver the right light:dark balance.
The most consistent benefit is seen with a 16L:8D cycle, which increases milk yield by 5–15% compared to natural or shorter photoperiods (Dahl et al., 2000; Lim et al., 2021). This response is mediated by elevated IGF-1 and improved mammary activity. Importantly, cows must also experience a defined dark phase; continuous light eliminates the benefit (Miller et al., 2000).
In contrast, dry cows benefit from a short-day photoperiod (8L:16D). This regime enhances immune function and mammary tissue recovery, preparing cows for greater milk yield after calving. Cows exposed to short days during the dry period and then shifted to long days postpartum consistently outperform those kept under long days throughout (Miller et al., 2000).
Young stock also responds positively to extended photoperiods. Providing 14–16 hours of light supports lean tissue growth, rumen development, earlier puberty, and stronger immunity (Adamczyk et al., 2024). This early advantage helps build a more productive future herd.
Though research is less extensive, evidence suggests that 14–16 hours of light improves average daily gain (ADG) and reduces stress, resulting in improved growth performance and meat quality (Jaborek, 2022).
Advances in lighting technologies can provide a more precise and cost-effective management of photoperiods. LED systems can replace fluorescent and halogen systems due to their energy efficiency, durability, and capacity for fine control of both intensity and spectrum. Modern LED units allow producers to deliver consistent long-day or short-day cycles year-round while reducing electricity use by up to 75% compared with legacy systems (Pranavi et al., 2025).
Beyond simple illumination, programmable lighting systems offer dynamic control of timing, spectral composition, and dimming, ensuring animals receive light exposure tailored to their production stage. Some barns now integrate sensors and automation, linking lighting with ventilation, feeding, and activity monitors to maintain optimal environmental conditions with minimal manual intervention. Emerging research on wavelength-specific effects—for example, blue-enriched light for stimulating activity or low-intensity red light for night use—points toward spectral tuning as the next frontier in precision livestock management (Lindkvist et al., 2023).
Despite clear benefits, implementing photoperiod management is not without challenges. Over-lighting or failing to provide a proper dark phase can disrupt circadian rhythms, reducing effectiveness and potentially stressing animals. Uneven light distribution also influences behavior and movement, as cattle may hesitate to enter poorly lit zones (Lindkvist et al., 2023). Upfront investment in LED infrastructure and control systems can also be a barrier, although long-term productivity gains and reduced energy, costs often offset these expenses (Pranavi et al., 2025).
Looking forward, precision approaches are emerging. Smart LED systems capable of adjusting spectrum, intensity, and timing promise to fine-tune light exposure across different cattle groups. Integration with sensors and automation could allow real-time monitoring of light levels and animal responses, ensuring consistency and reducing human error. Research into the role of specific light wavelengths—such as blue light for activity stimulation or red light for low-disruption night use—will further expand the toolkit. These innovations suggest that light management, once a neglected variable, is becoming a frontier in precision livestock farming.
Light is a biological regulator, not just illumination — it shapes circadian rhythms, hormonal balance, immunity, and productivity in cattle. Natural day length in the Northern Hemisphere varies from ~8 hours (winter) to ~16 hours (summer).
The optimal photoperiod for optimizing production goals varies by stage:
Thoughtful light management can offer (depending on the type of production system and housing) a high-impact tool to enhance welfare, growth, and farm profitability.
Dahl, G. E., Buchanan, B. A., & Tucker, H. A. (2000). Photoperiodic Effects on Dairy Cattle: A Review. Journal of Dairy Science, 83(4), 885–893. DOI:10.3168/jds.S0022-0302(00)74952-6.
Miller, A. R., Stanisiewski, E. P., Erdman, R. A., Douglass, L. W., & Dahl, G. E. (2000). Effects of photoperiod during the dry period on dairy cow health and subsequent lactation performance. Journal of Dairy Science, 83(4), 962–967. DOI:10.3168/jds.S0022-0302(00)74964-2
Lim, D. H., et al. (2021). Effects of photoperiod and light intensity on milk production and milk composition of dairy cows in automatic milking system. J Anim Sci Technol. 63(3):626-639. doi: 10.5187/jast.2021.e59.
Adamczyk, K., et al. (2024). Effect of light on dairy cattle in farm conditions – a review*. Ann. Anim. Sci., Vol. 24, No. 4. 1139–1151 DOI: 10.2478/aoas-2024-0052
Jaborek, J. (2022). Does photoperiod affect the growth performance of cattle? Michigan State University Extension. https://www.canr.msu.edu/news/does-photoperiod-affect-the-growth-performance-of-cattle
Lindkvist, M., et al. (2023). Effect of light intensity, spectrum, and uniformity on the ability of dairy cows to navigate through an obstacle course. https://doi.org/10.3168/jds.2023-23469
Pranavi, A., et al. (2025). Recent advancements of light-emitting diodes in dairy industries. Trends in Food Science & Technology. V. 160, 105018. https://doi.org/10.1016/j.tifs.2025.105018