Winter Barn Ventilation and Photoperiod

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Published on: March 21, 2017

Winter Barn Ventilation and Photoperiod
By Mid Maryland Dairy Vets

1 – Truth serum time—can you handle it? Cows and calves can handle cold temperatures. A big winter problem is a tightly sealed barn. If temperatures are in the mid-20s or higher with minimal wind, KEEP THE BARN WALLS OPEN! I understand that, ergonomically speaking, warmer barns are more comfortable for employees and make it easier to keep water and manure flowing. Barns are designed to be no more than 10°F warmer than outside temperatures. Once you exceed that temperature threshold, moisture and particulates build up in the air.

We must keep air as dry as possible. Poor ventilation combined with stale, moist air created a perfect recipe for a pneumonia outbreak. Bedding, animal waste, and exhaled air are major moisture reservoirs. Bed-packs and manure solids bedding, which has higher moisture levels than alternatives, must be properly managed. Even in the winter, ridge vents and louvers must remain open to allow warm, moist air to escape. Exhaust fans must run effectively through the winter months. You may provide a windbreak, but it is not necessary to close up all sides of the barn.

If one thing is certain, it is that we have a lot of uncertainty and variation in our current weather patterns. During extreme temperature swings, it is important to micro-manage curtains and fans in order to prevent a potential pneumonia outbreak.

2 – We are in the middle of winter so we must discuss long-day lighting or photoperiod control before the season transitions to spring. The benefits of a long-day lighting investment include higher milk production, improved heifer growth, and better quality and safer working conditions. Costs include higher feed costs, installation costs, and a higher electricity bill. However, the benefits of marginal milk outweigh the costs. Supplementing light during the short days of fall through spring (September through April) has the potential to increase milk by 8 to 10% (average of 5 lb). A long-day lighting program requires a consistent schedule of 16 to 18 hours of >15 foot-candles (systems are typically designed at 20 foot-candles) at cow eye level and 6 to 8 hours of darkness. After calving, the milk increase is realized after 3 to 4 weeks of exposure. Constant exposure is emphasized, so don’t forget the holding area and proper lighting over the feeding area and beds.

On the other hand, dry cows benefit from the exact opposite schedule—a short-day lighting/photoperiod. Dry cows housed under short-day lighting had a 7-lb improvement in milk production over dry cows housed under long-day lighting conditions.

Heifers constantly exposed to a long-day photoperiod have higher growth rates, experience earlier puberty, and improved mammary genesis.

Some preliminary studies analyzing LED lights suggest a 6-lb improvement in milk production compared with metal halide lights. LED lights also use less electricity, operate more smoothly at lower temperatures, attract fewer insects, have a better quality light spectrum, and are safer for the environment. Additionally, LED lights are more efficient and last longer.

Finally, employee safety, efficiency, and work quality improve with better lighting. The winter doldrums are real. When you work in relative darkness, work-related depression and anxiety are real issues.

Take the time to research lighting strategies on your dairy.

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