The innovation of automatic calf feeders has led to more group housing options for young calves. Keeping those calves healthy can be a challenge, particularly if a producer transitions from individual hutches.
“It is difficult to improve the environment for a baby calf beyond a hutch. Yet our industry has been moving away from hutches very aggressively in the past couple of years,” says Ken Nordlund, veterinarian and professor emeritus from the University of Wisconsin.
Nordlund outlined some areas dairy producers should focus on with calf housing at DeLaval’s VMS Pro event in Las Vegas in March.
Calf housing needs to minimize the risk of disease, he says, and improving ventilation is one of the best ways to accomplish this.
How to maximize air flow
Group housing ventilation isn’t about ventilating barns. Rather, it’s about delivering clean, fresh air into the space around each individual calf without a draft, Nordlund says.
Natural ventilation is commonly used because it is environmentally friendly, there aren’t mechanical parts to deal with and it can be cost efficient.
“There are some deficits to natural ventilation and we have to compensate for it,” Nordlund says.
Positive pressure tubes are an answer to the shortfalls of only using natural ventilation.
He estimates more than 5,000 calf barns have been fitted with positive pressure tubes in North America. “It’s been done without an advertising campaign. It has been one testimonial after another from one dairy family to another who have driven this thing,” Nordlund says.
After the installation of a positive pressure tube, farmers have noted the incidence of respiratory disease in their calves dropping 50% to 75%. In Germany, there is a government initiative to reduce antibiotic use; analysis of 62 calf barns using positive pressure tubes saw respiratory disease decline by 60%, Nordlund says.
“All of this suggests our naturally ventilated calf barns were not being optimally ventilated,” Nordlund says.
Natural ventilation depends on prevailing winds moving through eaves or open sidewalls into a barn.
When there is no wind it can create thermal buoyancy because the calves heat the surrounding air. The air will then rise out of the barn through the ridge opening. Unfortunately, on cold days calves typically won’t produce enough heat to create the air lift and it leads to stagnant, stale air in the barn.
“Natural ventilation works well most of the time, maybe 80% of the time,” Nordlund says. “These tubes are setup so they work 24/7, 365 days a year. They deliver a small amount of air into the area around the calf. I think that is the reason we see the respiratory effects that we do.”
When installing a tube Nordlund recommends positioning the fan outside of the barn to circulate fresh air rather than recirculating air from within the barn that might contain pathogens. Fans should change the air in the barn approximately four times per hour.
The tube size should be consistent so it evenly distributes air along the length of the barn. The size and amount of discharge holes in the tubes should deliver air to calves without creating a draft. Achieving these goals requires knowledgeable tube design, available through training programs offered by the Dairyland Initiative.
It costs $250 to $800 to purchase and mount a fan, and tube installation ranges from $7 to $50 per linear meter. The electrical cost to operate a 20" fan is approximately $438 per year at 10¢ per kWh.