Introduction
The dry period in dairy cows represents a crucial interval between lactations, during which the cow undergoes physiological and metabolic changes to prepare for the upcoming lactation. Red lighting, a novel management practice, has gained attention for its potential to enhance cow welfare, productivity, and reproductive performance during both the dry period and have effects throughout the next lactation.
Physiological Basis of the Dry Period
The dry period serves as a period of mammary gland involution, regeneration, and preparation for the subsequent lactation. During this time, the cow’s mammary epithelial cells undergo remodeling, clearance of accumulated milk components, and replenishment of secretory capacity. Additionally, the dry period allows for restoration of body condition, and metabolic adaptation to support future lactation alongside maintenance and growth of the unborn calf. The potential epigenetic effect this period has on the unborn calf is critical as it can affect growth rates, immune function and future lactations.
Role of Light Environment in Dairy Cow Physiology
Light plays a critical role in regulating various physiological processes in dairy cows, including circadian rhythms, hormone secretion, and behavior. Natural light cues synchronize internal biological rhythms and hormonal fluctuations, affecting reproductive cycles, milk production, and metabolic homeostasis. The photoperiod is the duration of light exposure within a 24 hour period. Cows are susceptible to photoperiodic manipulation with light suppressing melatonin secretion and darkness enhancing it.
Lactating Cows
Long-day lighting (16-18 hour periods of light with a 6-8 hour period of darkness) increases prolactin secretion, increasing milk production when compared to a 12 hour/12 hour cycle. This milk increase can be around 2 kg/day but also increases Dry Matter Intake (DMI), possibly by as much as 6%. Having at least 6 hours of darkness is crucial to delivering these benefits.
Target light intensity is 162-215 lux at 1 meter above the feed table surface as the milk production response needs consistent light intensities at the level of the cows’ eyes.
Dry Cows
In contrast, dry cows show responses to short-day lighting, (6-8 hours of light with 16-18 hours or darkness) with milk production in the following lactation increasing by as much as 3 kg/day. This is due to a greater expression of the prolactin receptor in the mammary gland during longer times of darkness. Increased prolactin receptor expression results in higher milk yield during lactation. Other benefits seen have been increased colostrum quality and quantity, partly due to increased prolactin receptor expression (quantity) and the improved immune function that has been shown (quality).
Implementing Lighting
Target light intensity for ‘day’ lighting is 162-215 lux at 1 meter above the feed table surface as the milk production response needs consistent light intensities at the level of the cows’ eyes. ‘Night’ lighting should be below 50 lux at the level of the cows’ eyes.
Timers are crucial as switching the lights on and off needs to be consistent each day.
Impact of Red Lighting
Red light, characterized by its longer wavelength and lower energy compared to white or blue light, offers unique physiological effects that are particularly relevant during the dry period. Cows lack red retina receptors, unlike humans, so are unable to see under red lights. However this doesn’t obstruct their ability to find feed and water. Consequently lighting barns with red lights enables humans to go about their nightly tasks while still providing cows with darkness.
Implementation Strategies and Considerations
Integration of red lighting into dairy cow facilities requires careful consideration of lighting design, intensity, duration, and management practices. Strategic placement of red light sources, such as LED fixtures or natural lighting filters, can optimize cow exposure and minimize energy consumption. Continuous monitoring of cow behavior, productivity metrics, and physiological parameters can inform adaptive lighting strategies tailored to individual herd needs and environmental conditions.
Conclusion
In conclusion, red lighting represents a promising approach to enhance dairy cow welfare, productivity, and reproductive success during the critical dry period. By harnessing the physiological effects of red light exposure, dairy farmers can optimize cow health, milk production, and herd management practices although further research is warranted to refine implementation strategies for diverse production systems. Ultimately, the adoption of red lighting technologies holds significant potential to advance sustainable and humane dairy farming practices worldwide.
Further Reading
Auchtung, T.L., Rius A.G., Kendall P.E., McFadden T.B., Dahl G.E. (2005) Effects of Photoperiod During the Dry Period on Prolactin, Prolactin Receptor, and Milk Production of Dairy Cows. Journal of Dairy Science,Volume 88, Issue 1, pp121-127.
Garip, R., Baspinar, N., Suvarıklı Alan, B., Garip, M., Coskun, P., Arslan, E. (2023) Effects of night lighting with red light on melatonin and milk quality parameters in holstein cows. Journal of Etlik Veterinary Microbiology, Volume 34, Issue 2, pp161-173.
Lindkvist, S., Ferneborg, S., Stahlberg, K., Bankestad, D., Ekesten, B., Agenas, S., Ternman, E. (2023) Effect of light intensity, spectrum, and uniformity on the ability of dairy cows to navigate through an obstacle course, Journal of Dairy Science, Volume 106, Issue 11, pp7698-7710
The Dairyland Initiative (2024) Photoperiod and Lighting. University of Wisconsin-Madison
University of Kentucky (2024) The Effects of Lighting Manipulation on Dairy Cattle Management | Animal & Food Sciences
