ventilation in hog building

Proper ventilation is important to maintain comfortable temperatures and humidity conditions inside livestock buildings. Experts say poor ventilation can lead to health issues, low animal performance and higher energy costs.

As winter rolls on, it’s important for livestock producers to keep watch on the ventilation situation in their livestock buildings. Kris Kohl, ag engineering specialist with Iowa State University, said good ventilation is important for a number of reasons.

“Ventilation in a barn is there to provide moisture control in the building and basically provide oxygen for the animals, foremost,” he said.

Moisture removal from livestock buildings is a key issue in winter, Kohl said. When the animals breathe, moisture from their lungs gets in the air, and getting that moisture out of buildings is important.

Kohl said humidity should be between 60 and 80 percent, with 80 being the “absolute max.” Keeping humidity down can cut back on airborne diseases.

“At 95 percent, the bacteria in the air, they can live about a year and a half,” he said. “If we get down to 80, they live for about a minute and a half.”

Teng Lim, an ag engineer with the University of Missouri, said keeping good ventilation in winter can help the bottom line.

“Poor ventilation can result in poor air quality, low animal performance, higher energy and operating costs, and lead to other problems including health issues,” he said.

During winter, producers are trying to save on heat and propane while maintaining good air quality, Kohl said. For growing finishing pigs, the cold weather rate for air flow is 10 cubic feet per minute. He said the fans are the key engine for getting air flowing through the inlets.

“To get it evenly distributed throughout, we need to have an inlet within 20 feet of all the space,” Kohl said. “If the building is 40 feet wide, you can go right down the center.”

This fresh air falls to the floor because it’s cold, dense air. Kohl said a mix of 10 parts interior air to one part outside air doesn’t cool the building too much.

“If you start seeing pigs congregating where the cold air is coming in, it might be a little on the warm side,” he said.

Producers should aim for 68 to 70 degrees inside totally slatted barns, Kohl said, while being as efficient as possible.

“What we really don’t want, the heater starts shooting out 400,000 BTUs per hour, overshoots, and the fan kicks on and it cools down rapidly,” he said.

Making sure inlets are open to the right width can help with this.

“To make sure of good ventilation,” Lim said, “producers should frequently check and ensure proper inlets, including locations of the inlets and matching inlet openings to the ventilation rate. Fans and heaters should be checked and maintained, dusty fans and loose belts means inefficient use of the electricity, and significant leakages can also cause poor ventilation and increase energy costs.”

In addition to adding to disease concerns, high humidity can also cause issues for the building itself.

“Condensation on steel surfaces, over 100 percent humidity, that tends to rot our buildings,” Kohl said.

Increasing air temperature by 20 degrees cuts relative humidity in half, Kohl said. Having proper insulation is also important in keeping conditions right.

“If they’ve got condensation issues inside the barn, it probably means that they’re lacking insulation,” he said. “It’s better to be a little cooler and dry than hot and wet.”

The variability of winter weather, especially in Missouri, means producers should be paying attention to and monitoring their ventilation and heating systems.

“Farmers will need to continue monitor the building condition and animal activities and performance to ensure acceptable and stable living conditions,” Lim said. “Routine and frequent inspection and maintenance of the equipment and controllers are critical to provide good environment and keep operating costs low.”

Ben Herrold is Missouri field editor, writing for Missouri Farmer Today, Iowa Farmer Today and Illinois Farmer Today.