Ventilation key to housing cattle over winter
It's the time of year when the incidence of respiratory disease in housed cattle is at its highest, writes Dr Huw McConochie.
Bovine respiratory disease is a collective name for diseases caused by a variety of pathogens and can be the cause of poor performance, compromised future performance and mortality. Environment plays a pivotal role in the onset of BRD which has significant financial implications for growing and adult cattle alike. By changes to housing design and implementation of an effective vaccination protocol the risk can be significantly reduced.
Weather conditions in the UK make it difficult to maintain a healthy indoor environment. High moisture levels, humidity, relatively high autumn temperature and poor ventilation make the environment in which cattle are housed ideal conditions for transmission of viruses and bacteria.
Adult cattle and calves require opposite environmental temperatures, however. Both require a continuous supply of clean air. As a general rule of thumb you should need to wear a coat in the adult accommodation and have to take it off in the calf shed.
Pre-ruminant calves generate little body heat and therefore require sheltered draught-free accommodation. In general, a calf shed will struggle to create sufficient heat to ventilate naturally. In this situation introducing clean air through a ventilation tube is the best option or for sealed buildings a negative pressure system may be an option.
Calves can be kept warm by increasing the depth of bedding, using infra-red heaters or simply using calf coats.
Adult cattle generate large volumes of heat and moisture dissipated by sweating and on their breath.
Correctly designed buildings will ventilate effectively and ensure that dirty moist air is expelled through the ridge of the building by the stack effect.
Buildings which do not satisfy the following criteria will fail to ventilate naturally and will require some form of mechanical ventilation:
A height difference between the eaves and ridge of 15ft or a roof angle of 22 degrees
A continuous ridge gap of two inches for every 10ft of building width
No neighbouring buildings or natural features shadowing the building. For every 1ft of obstruction height you need 10ft of clear space
The building is less than 28m wide
Open sides to maximise air flow
Improvements in environment will maximise performance, reduce veterinary costs and mortality in the cattle and maximise profits.
* Dr Huw McConochie is senior dairy specialist at Wynnstay
