The key principles of thoughtful barn ventilation: more than just fans

Thoughtful barn ventilation goes beyond simply hanging a few good fans. It is a complex science that our ventilation specialist Huw Jones has been studying for years. According to Huw , a good ventilation system rests on three core principles: air exchange , effective cooling velocity and ambient temperature drop. The question he asks, are you ventilating your barn or are you ventilating your cow?

Air circulation: fresh air for healthy cows

Air exchange includes not only the replacement of air in the barn with outside air, but also the extent to which air is exchanged at cow level . Insufficient air circulation can lead to irritations of the cows' airways. The presence of ammonia is a very good indicator here. We are referring to less than 25 PPM (parts per million) ideally . Anything above that can lead to:

Irritation to the lungs and eyes;
Obstruction of the trachea's cilia to effectively remove mucus containing viruses, bacteria, fungi and dirt from the lungs;
Dying of cells lining the airways;
Reducing the covering tissue of the hoof, increasing the risk of claw problems.

You can very easily assess for yourself whether you have excess ammonia in your barn. For example, if your clothing retains barn odour, it is an indication that air circulation is inadequate and the health of your cows may be at risk.

It is important to realise that this is not just about the air exchange in the barn, but definitely the air circulation per cow. This involves looking at how much air you move through the barn based on the number of cows in that barn. It is important to remember that cows are fresh air animals, and their demand for it is very high. A cow biologically is very inefficient in terms of lung volume per kg of body weight. Due to the rumen increasing in size over centuries of breeding, this caused the lung volume to decrease and therefore putting the cow under more pressure to supply her body with oxygen.

In the table above, you can see what our targets are when it comes to air circulation in the US/Europe in fully mechanically ventilated facilities In naturally ventilated facilities we are simply inferring exchange with the use of pressurizing fans and recirculation fans

Effective cooling rate: air speed for comfort

While temperature and humidity are incredibly important, air speed is a crucial factor when it comes to ventilation. A minimum air speed of 1 m/s at head height of the cow contributes to a comfortable wind chill. Although this does not lower the physical air temperature, it has a positive effect on how cows perceive the temperature. Typically we like to achieve 2m/s air speed at the cow furthest away from the ventilator.

It is crucial air speed is measured at cow level, otherwise what is it doing for her? Take a look at our ECV Fan here!

Currently, cooling rate is not yet included in THI calculations. Only humidity and temperature are considered. However, our research shows that every 0.44m/s of cooling speed on the cow, sensitively lowers THI by 1.1 THI.

Lowering temperature: lowering temperature with water

Water can be used to lower both cow and ambient temperatures. Using water to lower the cow's temperature is called soaking. A successful soaking system consists of five essential components:

Automation: Minimise labour hours with automated systems, which will also ensure you don't cool cows too early or too late.
Spray: Make sure the spray capacity is suitable to completely cover the cow. The angle at which you soak is also very important to ensure that you spray on the cow and not on the feed.
Preventive approach: Prevent problems by taking proactive measures and soaking before the cow suffers from heat stress.
Run time: Optimise the run time of the soaker. ideally it is around 7 minutes. As temperatures rise, the time the soakers are off decreases.
Combination with fans: Many studies have shown that soaking is remarkably more effective when combined with fans.

Water can also be used to lower the ambient temperature. This can be done through high-pressure misting.

Where to start in your barn: a strategic approach

Now that the three core principles are clear, we can imagine that you are not so sure where to start. A strategic approach is crucial. Therefore, we would like to list for you which part of ventilation has the highest priority:

Cubicles: First of all, ensure optimal air circulation around the cows' cubicles. This is where the cows spend most of their time, ideally 14 hours, and where you also want them to be as much as possible. So good cooling is by far the most important here. When you use milking robots, this place is obviously also very important.
Soaking in the feed alley: Implement a well thought-out soaking system in the feed alley. Soaking always comes before ventilation, but only really becomes optimal when combined with fans. Therefore, steps 2 and 3 should actually be combined, but soaking always comes first.
Fans in feed alley: place fans strategically in the feed alley for targeted air speed .

Ofcourse it is very important to remember the what groups are most important on the farm

Holding pen – this is the area of the farm with potentially the highest kw of heat per metre squared. Each cow covers around 1.4m2, so you can understand why heat stress is such a problem here. It is great to have a well ventilated barn, but unless your holding pen is adequately ventilated,you will still face some of the challenges of heat stress.
Dry Cow Pen- these girls need the best care possible. Heat stress within the dry period has been proven to decrease milk production in the cows subsequent lactation, as well as decrease their offsprings performance for up to 2 generations! A heat stressed dry cow can lead to problems for years, not months!
High Lactating animals- these animals are a very close 3^rd behind dry cows. We want to ensure these animals receive great cooling to ensure reproduction and production performance is kept to a high level during warmer months.

Conclusion: barn ventilation does not equal cow ventilation

In a nutshell, it is clear that barn ventilation is not synonymous with cow ventilation. Avoiding wasting energy on non-directed ventilation and preventing water wastage when soaking cows are crucial considerations for making your barn as sustainable as possible too.

A well-designed ventilation system is the key to healthy and comfortable living conditions for dairy cows. It not only contributes to their well-being, but also pays for itself in the long run in improved productivity and cattle health. Investing in the right barn ventilation is investing in the future of your dairy farm.

I want to start ventilating my cows!

After reading this article, are you curious what ventilation can do for your cows ? Or are you curious whether your current ventilation system is optimal? We would love to take a look with you! With our years of experience and expertise, together we will make sure your barn is functioning at its best.

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