Cross-ventilation barns require more maintenance but offer a more consistent environment during summer heat stress.
Cross-ventilated barns offer more consistent environments for cows
Cross-ventilated or naturally ventilated barns? It can be difficult to answer that question, since cross-vent and naturally ventilated barns are often managed differently. Questions surrounding production, heat stress and reproductive rates can often be compared in a general sense.
But questions by veterinarians about pneumonia and respiratory health are more difficult to answer because of record-keeping disparities among herds.
John Vosters, vice-president and livestock manager for MilkSource, which milks 22,000 cows at five locations in central and eastern Wisconsin, is in a unique position to answer these questions.
MilkSource milks thousands of cows in each type of barn, using similar management systems and centralized record keeping. As a result, Vosters can readily compare each system’s pros and cons.
- Heat stress is less pronounced in cross-vents. In the summer, MilkSource uses cooling pads on the air inlet side of the buildings, which cool the air as it’s drawn across the building. "There are fewer peaks and valleys in production in the cross-vents," Vosters says.
"We’ll generally see a milk drop of 3 lb. to 4 lb. per cow per day in the cross-vents during hot weather," he says. "In the naturally ventilated barns, it’s often 9 lb. to 10 lb. per cow per day."
- Respiratory events such as pneumonia are about half those of naturally ventilated barns.
- Conception rates are almost always higher in cross-vent barns. "Heat stress is definitely a drag on breeding in naturally ventilated barns," Vosters says. "We will catch up on our pregnancies in the fall, but that creates a roller coaster in numbers in our cow calving groups. The cross-vents are much more consistent."
Water on feed lane floors is lower in cross-vent barns because the cooling pads reduce the need for sprinklers. In naturally ventilated barns, sprinklers keep the floors wet much of the summer. As a result, naturally ventilated barns have more issues with foot health. The extra water used for cooling eventually drains into the manure system, which can add thousands of gallons of water that must be pumped or hauled away.
- Cross-vent barns have higher operating costs. Some ventilation fans must run continually, even in winter, to keep air moving.
- Each barn has about 20 2-hp pumps that move water through the cooling systems, resulting in higher electrical costs.
- "Cooling pads take weekly maintenance," Vosters adds. "In summer, we drain the systems once a week to make sure none of the water lines are plugged. And we wash the pads monthly to ensure air movement."
- Cooling is less effective during times of high humidity because the cooling pads are trying to add water to air that is already heavily laden with moisture.
- Cross-vent barns look like big warehouses. From a public relations perspective, consumers might view the structures as less cow friendly.
Bottom line: When asked what his next barn will be, Voster’s answer is immediately: "Cross-vent."
- May 2013