Turbulence ventilation may be the next big thing in dairy industry
By Carol Stender
cstender@agrinews.com
Date Modified: 02/16/2012 9:37 AM
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ST. JOSEPH, Minn. — Cross and tunnel ventilation is in vogue, but veterinarian Gordie Jones predicts turbulence ventilation will be the next hot topic for livestock barns.
Although turbulence ventilation hasn't been installed in any barn yet, the concept offered dairy farmers attending the Dairy Management Workshops in St. Joseph food for thought.
Jones is a partner in Central Sands Dairy in Nekoosa, Wis. The dairy uses natural ventilation, he said. The barns have curtains, an open ridge in the ceiling and fans over the feed aisles to move air.
Turbulence ventilation, developed by a mechanical engineer at DDI in Dubuque, Iowa, uses positive pressure. Air is blown into the barn from all areas uniformly, Jones said.
Heat transfer from a cow is influenced by speed and direction of air, he said. Turbulence ventilation uses turbulence to increase the heat release form the cow during hot weather. The convective heat transfer increases 50 percent in hot air.
Cows convert carbohydrates to protein. The by-product of conversion is heat. Heat is removed from the cow through controlled breaths per minute.
The concept offers three-dimensional airflow. Air blowing into the building from all sides creates big whirls of air which, in turn, create little whirls that feed on their velocity.
Mechanical systems, like tunnel ventilation, have one dimensional air flow. In cross-ventilated barns, the air is cleanest as it enters, but quality deteriorates as it travels to a barn's maximum width. The air flow is also interrupted anytime barn doors are opened, he said.
Good air quality means healthy cows.
Jones has practiced veterinary medicine in Michigan and Wisconsin and is a consultant on dairy construction, design and cow flow. He has consulted with dairies suffering from high pneumonia numbers. One farm, with 4,000 cows, reported 9,000 pneumonic events annually, he said.
One farm had to vaccinate cows four times in one year.
His farm had 18 pneumonic events, he said.
Jones also noted summer milk loss due to heat. His cows suffered a 2 to 3 pound loss due to summer heat with recovery in less than a week with the naturally ventilated barn. Besides the fans on the feed lanes, the barns have a soaking system with two minutes on and six off.
Some farmers with mechanically ventilated barns told Jones they were losing 10 to 12 pounds with recovery occurring in September.
When a producer said he had little summer milk loss and good reproduction in his barns, Jones added that cross ventilation on a 600-cow dairy can work, but it's more difficult for good air movement in barns wider than 200 feet.
Turbulence ventilation could offer reduced days below freezing in free-stall buildings, he said. Traditional natural ventilation has no control and over ventilates during cold weather. Heat is lost in the exhaust air and with heat rising to the ceiling money is wasted.
Positive pressure supply systems are simpler because they use entry and egress openings for discharge points, he said. Iit offers better health to animals with uniformity in room temperature. Uniformity prevents regions of the barn from being too hot or too cold.