In our previous blog on preparing for winter housing we looked at ventilation and moisture management. In this follow on blog we’ll discuss in more detail two other key considerations when looking at building function: wind speed (draughts) and temperature;
1. Wind Speed (Draughts)
Whilst good ventilation and the need to get fresh air into a shed is vital, this air flow needs to be uniform and draughts must be avoided particularly when housing young calves. Draughts will increase the calf’s lower critical temperature (LCT); the temperature at which it starts having to use energy to stay warm. For a four week old calf housed in a draught-free environment (wind speed 0.2m/sec) the LCT averages 00C. In a draughty environment (wind speed 2m/sec) this increases to 90C. This means once the temperature drops below 90C calves housed in the draughty shed would need to be fed more to keep target growth rates on track. If not, growth and development will be negatively impacted.
Ref: Jamie Robertson. Livestock Management Systems
The basic rules for controlling wind speed:
a. Create a draught-free zone at animal height
b. Use solid barriers with no gap at the bottom
c. Provide enough bedding to allow young cattle to ‘nest’
d. Fill in gaps underneath sheeted gates
e. Use windbreaks where stock are exposed to predictable elevated wind speeds
As a short-term measure, large straw bales can be provided to offer some shelter. For longer-term measures, investment in permanent windbreaks should be considered. Pay attention to the inevitable increase in airspeed elsewhere once windbreaks are fitted. Windbreaks must be kept clean in order for them to function as an effective inlet - if the gaps become blocked with dirt or vegetation, ventilation will be affected.
Examples of windbreak materials which allow varying amounts of fresh air through in a controlled manner:
Temperature is a particularly important consideration for young calves. Housed in big airy buildings, young calves may simply not produce enough heat to drive the stack effect. And they are more vulnerable than older calves to cold stress. Look for ways to reduce drafts and possibly create ‘micro-climate’ environments for young calves, and ensure pens are well bedded to enable them to ‘nest’. Quartz linear heaters can be used to warm up sheds, or calf jackets can be helpful in preventing calves from becoming chilled when temperatures drop. They can also be useful as an aid for calves which are unwell, and therefore more at risk from cold stress.
As we said before, winter IS coming, so now is the time to appraise your buildings with a critical eye and ask yourself the question, are they truly fit for purpose? And if not what changes can you make to reduce the risk of disease in your animals during the winter housing period. In some cases small and inexpensive alterations can have a very positive impact on animal health. For further advice, speak to your vet or check out the AHDB beef and lamb website where you can find some excellent information on winter housing.
For further information please see the product’s SPC or contact your veterinary surgeon or Zoetis UK Limited, Walton Oaks, Dorking Road, Tadworth, Surrey KT20 7NS. http://www.zoetis.co.uk/ Customer Support: 0845 300 8034 Use medicines responsibly (www.noah.co.uk/responsible) Date of Preparation: Aug-16