Course: Winter Health | Last Updates: 7th October 2015
Housing cattle does require caution, and unfortunately we are going wrong on a massive scale in the UK because buildings aren’t providing the environment we are hoping for.
About 50% of cattle housing, both new and old, is not fit for purpose, which is creating many health and production problems.
It is not what cattle housing looks like, but how it works which is the issue, and identifying where the problems lie is half the battle. Most of the solutions are not rocket science, and can be achieved fairly easily.
The absolute fundamentals involve getting fresh air into the unit, controlling air speed and controlling moisture in order to protect the animal and provide an environment which does not support bacteria and viruses.
Why is good ventilation important?
We need fresh air to replace and drag out stale air and remove excess heat and moisture as part of the ventilation.
Bacteria and viruses are present in stale air, but much less so in fresh air. Respiratory viruses will survive only 4-5 minutes in fresh air, while in air which is only 50% fresh they can survive 10-20 times longer.
There are parts of buildings which will have gallons of fresh air, while there will be pockets of rancid air, so it is worth being aware of and trying to identify danger areas.
However, while too little air can be a problem, too much air can also cause issues, so farmers must keep control of air speeds in the building.
The impact of air speed is the single-biggest environmental factor affecting youngstock: a draught-elevated air speed of walking speed will increase a calf’s lower critical temperature – the lowest temperature it can tolerate before having to use energy to keep warm – by 9C.
When an animal is having to use energy to keep itself warm, not only will it not gain weight as quickly as it should, but also the immune system can become weakened making the animal more susceptible to illness.
Why is moisture control important?
This is extremely simple in terms of biology. If you are rearing adult cattle, they produce huge amounts of moisture. A single animal produces 50 litres of moisture from the back, and 10 litres through respiration. If you have 100 cows, that’s 6 tonnes of moisture a day.
Having a lot of moisture about causes huge problems as it is the perfect breeding ground for viruses and bacteria, causing problems such as environmental mastitis, pneumonia and foot issues.
Moisture also makes a building colder than it needs to be. Damp isn’t a problem in the summer, but in winter it can be hugely problematic, especially for calves.
Adult cattle produce huge amounts of heat through their digestive system, meaning they have a lower critical temperature of 20C.
Milk diets are fantastically digestible, but they don’t produce a lot of heat at digestion. A four-week-old calf has a lower critical temperature of about 15C.
Therefore when the environmental temperature is below 15C a four-week-old calf will start to burn additional energy to keep warm.
Going back to moisture, if a calf is in damp conditions, lying on a damp bed, its lower critical temperature goes up by 6C meaning it starts to burn additional energy to keep warm when the environmental temperature is below 21ºC.If nothing else, it’s inefficient to keep animals in a draft and in the damp.
How can you improve moisture control?
There are a few basic rules to follow which can drastically improve winter housing and none of them are particularly complicated to achieve. It simply requires a proper diagnosis of the building.
The first is to sort the floors out to reduce moisture. People can cut channels in existing floors to make simple drains to drain water and waste away, or they can cut channels in front of rows of calf pens so debris drops into the channel.
These ensure the space between calf pens isn’t wet, so straight away the building is warmer.
With older cattle, if you suffer from environmental mastitis make sure that urine is properly drained away. Straw is too expensive to use as a solution and to allow these inefficiencies.
How can you improve ventilation?
You want fresh air in a building, but not gales, so you need to look closely at ventilation and think about how weather can help. If you have a great big opening it will create a wind tunnel and have a negative effect on the cattle.
When wind enters the building you must control the speed. To do that all walls must be solid to animal height, and if you use a shuttered door use something such as rubber to fill the gap at the bottom.
It’s as much about the wind available to you as an art of science. You should have a solid sheet above the wall, but it requires a gap which differs depending on circumstances.
Most of the year the building is ventilated by wind, so the issue is how to get it moving around without being too windy.
You can use space boarding or perforated sheeting and gale breakers to help. They all have different technical properties and which is best depends on the exposure of the building and the amount of space above the wall, so it can be worth seeking advice on which is right for you.
Ventilation mainly happens at ground level when the wind is blowing, but it also needs to work when the wind isn’t there. At that point, you rely on the stack effect.
For the stack effect to work you need a hole in the roof so that warm air rises, creates a negative pressure and draws the fresh air in.
You need to ensure the hole is big enough: as a ballpark, an adult animal will need 0.1m2 in the roof, so 100 cattle will require 10m2. More detailed information on housing and help to calculate the figure is available from DairyCo.
If you find the whole will be over cubicles of youngstock, you need to install a covered open ridge.
I’m confident a lot of existing buildings need to be opened up in the roof or side wall, but when you do open it up it has to be done in a way that protects the animals.
Is there anything else to consider?
Hygiene of housing is hugely important, especially with youngstock. Ensure surfaces can be properly cleaned to minimise the presence of viruses and bacteria and reduce the risk of illness.
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