Fresh air keeps bugs at bay
Fresh air keeps bugs at bay
Minor modifications can
bring big improvements to
the level of ventilation in
dairy cow housing and
reduce the risk of disease
spread. Jeremy Hunt reports
SPACE-BOARDING along the sides of dairy cow buildings fails to provide adequate ventilation when the gap between boards is 1.25cm (0.5in) or less.
When space-boarding is erected, it is common practice to use the width of the depth of the board to measure the gap as the boards are being fixed in place, says Shropshire-based dairy consultant John Hughes. "But that is useless and will not provide the correct level of air flow through the shed."
Adequate ventilation is essential to reduce risk from many diseases and producers must not assume keeping cows enclosed and limiting air-flow inside the shed will provide them with more protection against foot-and-mouth.
"Bugs will creep in and be locked in a stale atmosphere where they can thrive. It is far better to keep the air moving and try to create an environment that is as near to outdoors as possible."
He says it is important for dairy farmers to be aware that they will not achieve enough ventilation in dairy cow housing with a gap that is less than 3.75cm (1.5in) between space boards.
"Anything less than that and there wont be any air movement. When cobwebs can be see strewn between space-boarding it is clear proof that there is no air movement," says Mr Hughes.
But what about buildings that are taking the brunt of prevailing winds? "That is when true Yorkshire boarding should be used. The term is often used to cover all types of space-boarding but in fact true Yorkshire boarding is specific in its design."
Mr Hughes says Yorkshire boarding is constructed with vertical boards fixed 3.75cm (1.5in) apart with further protection provided by a second row of boards which must be fixed to be proud of the first row.
"That is real Yorkshire boarding; the second row of boards deflects the air and although it provides protection from prevailing winds it does not impinge on the level of ventilation."
But producers having to cope with modern, wide buildings with a low pitch and a low height to the eaves may have to resort to other methods to improve air flow.
"Removing the ridge cowls and trying to create an upsweep of air from within the shed is unlikely to work on its own because of the low pitch of the roof and the width of the building.
"In this case it is advisable to cut a gap in roof sheets at the point at which they overlap. The gap has to be made on the overlap of the sheets."
"But it must be not be made on the sheets themselves or they will be weakened," he warns.
"This will also give greater stability to the roof and will allow air to pass through the gaps and reduce wind pressure against roof sheets."
Mr Hughes says that professional help sought to do this job will only involve a few hours work. "But I can assure anyone that the difference will be amazing."
Another option is to reverse the roofing sheets to create a 19mm (0.8in) gap between each vertical line of sheeting. "There will be no risk of rain entering the building because of the speed and density of the circulating air from inside. As air exits the shed, it will divert any falling rain."
Where new buildings are under consideration or where alterations are an option, Mr Hughes recommends air space and loafing room should be a priority.
"Cows are bigger than ever, they are housed for longer and are producing more slurry. Slurry passages need to be at least 10ft wide and feed passages should increase from 10ft to 14ft."
But Mr Hughes says more thought should be given to providing housed dairy cows with access to an outside exercise area during winter. "Providing cows can eat and lie under cover they will be far healthier when they can stretch their legs and get some winter sun on their backs by being given access to an outside loafing area.
"And when cows are gathering at the door of the building in spring, do not be naive and assume that they are smelling the new spring grass. It is simply that they are desperate to take in some fresh air as the temperature is rising inside the shed.
"When you see them at the door take a look inside; if you have got cobwebs hanging from the roof your ventilation is inadequate and the health of your herd is at risk." *
IMPROVINGVENTILATION
• Correctly spaced boarding.
• Openings in roof.
• Consider outdoor loafing area.