University of Wisconsin - Extension

Dairy cows in northern regions like Wisconsin, give more milk if they get extra lighting during the winter months, when days are short. According to Scott Sanford, an outreach specialist in Biological Systems Engineering at University of Wisconsin-Madison, the increase in production is, on average, 4 pounds a day for each cow.

Farmers who are considering leaving the lights on should provide lighting so cows get about 15 to 20 foot-candles of light for 16 to 18 hours each day. Sanford said cows getting extra light during the winter eat, on average, 4 percent more.

"It is very important to turn the lights on and off at the same time each day," Sanford said. "It's best to use an automatic timer."

Sanford recommends using high efficiency lamps and said that "Focus on Energy" has grants that could help farmers pay for them. Information is available at 1-800-762-7077 or to http://www.focusonenergy.com .

In a tie stall barn, you can use one continuous row of single bulb T-8 fluorescent lamps or two bulb T-8 fluorescent lamps every 8 feet in water resistant fixtures on the ceiling over the cows' heads. In a freestall barn, Pulse Start metal halide or high pressure sodium lamps are recommended but one should consult a lighting contractor about proper placement.

Sanford said the payback time for installing and using long-day lighting is about two years for a 40-cow herd and just six months for a 300-cow herd. This practice will increase feed costs, but results in an increased profit of about $62 to $67 per cow per year.

For more information on lighting for agricultural buildings, refer to UW-Extension publication "Energy-Efficient Agricultural Lighting" (A3784-14), which can be found at http://cecommerce.uwex.edu/ under the heading "Agriculture" and sub heading "Energy, Engineering, Environment, Safety". For more information about long day lighting in dairy barns, contact Scott Sanford at 608-262-5062, sasanford@wisc.edu or ask at your local University of Wisconsin-Extension office.