"This study's goal was to add to the knowledge base regarding the energy use, controls, possible galactopoietic effects, and economic feasibility of long day lighting (LDL) on a large commercial dairy farm. The implemented system maintained a minimum illumination level of 160 lux (15 foot-candles) for 16 hours and 40 lux (4 fc) maximum for 8 hours on a large dairy farm in Michigan that milks approximately 1,100 cows. The system used dimmable 150-Watt high-bay luminaires, dimmable 60-Watt canopy luminaires, and a dynamic control system. The control system used daylight harvesting to save energy, dimming the LED luminaires when natural light was available in the barns. The LDL system used 67% less energy than a theoretical system with metal halide HID luminaires, and 52% less energy than an identical system with LED luminaires but no dynamic controls. Due to unforeseen challenges, there were only 3 months of original milk production data available that could be compared with post implementation data. Analysis of the 300 highest producing cows showed an estimated 10.5% increase in milk production over July-September 2019 compared to July-September 2018. Using the estimated 10.5% increase in production, the implemented system would have a payback period of less than one year. If the estimated increase is maintained for one year, the production increase would be equivalent to adding 32 more cows to the highest producing groups. The estimated 32 cows that were matched in this calculated production increase would have produced about 13,000 pounds of CH4 annually, which is equivalent to approximately 331,000 pounds of CO2e."--Page ii.
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