Building trust in food begins with empowering farmers through one of the largest and most diverse conservation- and sustainability-focused public-private partnerships in our nation’s history: America’s Conservation Ag Movement. To find the latest news and resources related to the Movement, visit AgWeb.com/ACAM.
A conversation Gabe Middleton had with a mentor a few years ago struck a chord with the large animal veterinarian.
“He said when you leave a conference, you should have something you can take back to your clinic that helps clients and makes money,” recalls Middleton, a partner in the Orrville Veterinary Clinic, Orrville, Ohio.
For Middleton, one of those “somethings” became the use of positive pressure tube ventilation (PPTV) systems in dairy calf and heifer facilities. The systems reduce air bacterial counts and noxious agents in barns by driving fresh, outside air into the microenvironment of the calf.
By improving the air ventilation, Middleton’s experience and industry research show dairy calves are more likely to thrive and have fewer incidences of bovine respiratory disease (BRD).
“If the dairy’s stocking density, nutrition and vaccination protocols are adequate, we typically see about a 50% reduction in respiratory disease cases,” Middleton says.
The financial benefits from fewer BRD incidences can be significant. A recent study by Elanco involving 104,000 heifers from 23 herds with one or more recorded cases of BRD during the first 120 days of life, showed costs from the infected heifers exceeded those for healthy heifers by $212 to $237. Total costs depended on whether anticipated milk-production differences were considered, according to Elanco veterinarian Michael Overton. Those estimates greatly exceed previously published figures ranging from about $20 to $60 per head in BRD costs. (Read more about the study here https://bit.ly/3c4pSDZ)
Middleton likes to reference studies such as a 2012 paper by F. Soberon that shows the positive impact that reduced BRD incidences have on milk production (Learn more at https://bit.ly/2XAQwPL). Studies such as this show that every 0.1 pounds of preweaning average daily gain (ADV) can lead to approximately 300 pounds of L1 milk. In addition, another study Middleton references shows healthy calves not receiving antibiotics produce 1,000 pounds more milk in L1.
In addition, Middleton says by reducing BRD cases producers experience fewer death losses, lower heifer replacement costs and a reduction in veterinary expenses.
“Instead of needing to treat a sick calf, what we’re doing is helping the client prevent a sick calf to begin with,” Middleton says. “All of these factors add up to helping dairies become more profitable, which is what I believe we’re here to do.”
What the system accomplishes is critical to its success in helping reduce the incidence of BRD. The system must be designed and installed so it blows 100% fresh, outside air into the calf room and without creating a draft.
The components are straightforward. Essentially, there are three primary components in a positive pressure ventilation system: a fan, a tube and cables that suspend the tube from the rafters.
During the design phase, account for three key physical properties within the tube, Middleton notes: the fan’s static pressure, and the tube’s aperture ratio and discharge coefficient. Without going into a lot of detail, just remember if the system is not designed with these factors in mind, you can end up with a poor match between the fan and the tube. Ultimately, this can result in poor air flow through the tube and uneven air distribution at calf level.
While the concept of a PPTV is straight-forward, the size and shape of the barn and how well the system is designed and installed will impact performance. Middleton encourages practitioners to steer producers in the “right direction” regarding the design.
“Too often, producers may choose to save money by purchasing a cookie-cutter system that is not designed specifically for their facility,” he cautions. “That invariably leads to disappointment in the performance of the system.”
He notes the University of Wisconsin Dairyland Initiative spreadsheet is a good reference tool for design and is available to trained consultants. A document explaining what information is needed to put together a design is available here:
Several companies also manufacture systems, including ADC, Badgerland Supply and J&D Manufacturing. (Please note that these companies provide manufacturing for the system and typically not the installation.)
Dairy producers can anticipate spending between $1,000 and $5,000 to put a PPTV system into place, depending on the size of the barn. That cost includes the electrical work involved as well as hard costs for the fan and tube.
“I know cash flow can be a problem these days, but if you do the economic assessment, it’s really a pretty easy decision for dairies to make,” Middleton says.
For the economic piece, he suggests evaluating the dairy’s records and also considering indirect costs the dairy has likely experienced in recent years, such as early culling.
“When that animal has to go to the sale barn at 6 months of age, all that money the dairy invested is lost because they don’t get much money for her, not to mention the time and expense they incurred with her up to that point,” he notes. “My experience is that producers are really happy with these systems.”
Evaluate effectiveness over time. A PPTV system is only as good as the results it achieves. Middleton says while not all practitioners have access to equipment to directly test air bacterial counts, simple observations are often very helpful. Here are three steps he recommends.
1. Evaluate the fan to determine if dust build-up or other objects are impeding air output.
2. Check the tube for tears or ripped holes. Tears most commonly occur as the tube exits the fan shroud.
3. Consider the location of the fan and holes.