Guide to choosing a ventilation system for your dairy unit – Farmers Weekly


Fans are an essential consideration for all housed dairy methods the place cows could also be topic to intervals of warmth stress that might negatively have an effect on well being and manufacturing.

Heat stress is attributable to a mixture of warmth and humidity and is measured by the temperature humidity index (THI).

In damp, humid environments equivalent to these skilled in components of the UK, warmth stress can happen at comparatively low temperatures as the flexibility for the cow to “dump” moisture from the physique into the atmosphere to cool herself decreases.

See additionally: A information to mitigating warmth stress in housed cattle

According to Cargill, fertility traits are affected as soon as day by day common temperatures exceed as little as 14C (THI 57), and conception charges can fall from 20C (THI 65) when relative humidity is 60%.

Fans cool cattle by growing the air velocity throughout their our bodies and elevating the speed of warmth loss. Even when a shed is of course properly-ventilated, there’ll nonetheless be days when warmth stress is a drawback.

Below, Ivor Davey, director of CowPlan; impartial guide Sam Evans; constructing specialist Jamie Robertson; and Robin Hibberd, technical gross sales engineer for Hydor, share their key concerns when investing in followers.

Points to contemplate

1. High power prices shouldn’t be used as a motive to keep away from putting in followers. Running followers does price when it comes to electrical energy use, however not working them might have an hostile impact on well being and manufacturing.

2. Ensure pure ventilation is working first. Air modifications, reasonably than circulating stale air, are wanted to ship a true cooling system.

3. Look at return on funding – what number of days within the 12 months will followers be wanted?

4. Install humidity loggers (accessible from about £20) at key factors within the shed the place cows focus – for instance, within the gathering yard. This will assist decide the place to goal followers to give the very best return on funding.

5. Consider complete set up prices, together with wiring, working and servicing.

6. Is there adequate energy provide to service the followers?

7. Consider putting in an automated variable-velocity management field based mostly on the temperature within the worst a part of the constructing. This will allow the followers to velocity up or decelerate relying on necessities, and assist decrease power use.

8. Where is the air generated by the followers going? Dirty air wants to exit the constructing to keep away from inflicting well being points.

9. Look on the quantity of air generated by particular followers and work with suppliers and advisers to decide the situation and top of the followers so that they ship the required outcome.

Types of fan

All producers have their very own variations that may differ barely and carry their particular model title. However, broadly talking, they have an inclination to fall into the next classes:

1. Belt-driven followers

Size varies, up to greater than 2m in diameter. These followers can have a casing round them to cease air going sideways and are hung at a slight angle on chains in rows alongside a shed, usually above the cubicles.

Air is blown in the identical course because the prevailing wind. The concept is to take air from one level of the shed and push it over the backs of the cattle till it exits the constructing.

Belt-driven fan

Belt-driven fan © Ivor Davey/CowPlan

Pros and cons

✔ A number of air pushed utilizing a small quantity of electrical energy
✔ Can have louvres/fins which direct air out of the entrance of the fan
✔ Can be used on their very own to take care of a “hotspot” in a shed – for instance, in entrance of a robotic
✗ A sequence of followers wants to be hung when cooling cows over a giant space
✗ Must be angled appropriately so air goes throughout the backs of the cattle
✗ May not be appropriate in low sheds
✗ Less air is projected sideways, so a number of rows of followers could also be wanted

2. High-volume, low-velocity followers

These are giant helicopter-model ceiling followers that blow air downwards on the cattle.

High-volume, low-speed fan in shed

High-volume, low-velocity fan © MegaFan

Pros and cons

✔ Capable of transferring excessive volumes of air
✔ Blow air down and outwards. The fan could be reversed, however loads of air outlet can be wanted
✗ May stir and blend air, reasonably than create a draught
✗ Could disrupt ventilation throughout a constructing if the shed is ventilated by pure air motion
✗ Not focused
✗ Restrictions on clearance from the ends of the blades to an impediment (for instance, a wall) and between followers. Work finest in clear-span buildings

3. Plate followers

Plate followers are put in throughout the wall at one finish of a shed to suck air from outdoors into the shed.

Pros and cons

✔ Plate followers can work if there’s a hotspot within the shed, equivalent to a gathering yard or subsequent to a robotic, however they don’t seem to be appropriate for cooling over giant areas
✔ A constructive strain tube could be added in low-roofed cow sheds to ship air throughout the entire constructing. The measurement and course of the holes within the tube, and the scale of the fan, will want to be designed particularly for grownup cow necessities
✗ An particular person fan is usually put in to cool cows, however could not herald sufficient air to cool the shed
✗ Think in regards to the top of the fan. If it’s excessive above the cows, it might assist with ventilation, however won’t cool animals

Panel followers

Panel fan are comparable to belt-pushed followers, however should not housed in a field.

Panel fan

Panel fan © Ivor Davey/CowPlan

Pros and cons

✔ May be extra appropriate for wider sheds the place air circulate doesn’t want to be directed
✔ Smaller than belt-pushed followers, so take up much less room
✗ Thin, round casing doesn’t cease air going sideways and doesn’t have fins to direct the air
✗ Less quantity of air produced from every fan, so extra followers could also be wanted

Basket followers

These seems like typical workplace followers, and are housed in a cage or basket.

Pros and cons

✗ Nothing to cease air going sideways
✗ Not very environment friendly
✗ Do not obtain throw and distance so extra followers are required

Guide to fan prices

Guide fan prices (* = costliest, ***** = least expensive, information solely, complete working prices will range relying on measurement of shed, variety of followers used and tariff)
Fan kind Fan price Electrical working price/fan Electrical working price/shed
Belt-driven fan ** ** **
High-velocity, low-velocity fan (helicopter fan) * * ***
Plate fan **** *** *
Panel fan *** *** *
Basket fan ***** *** *
Source: Robin Hibberd, Hydor. Note: High-volume, low-velocity followers are costlier/unit, however fewer are wanted in every shed which reduces the working prices on a shed foundation. A better variety of plate, panel and basket followers can be wanted throughout a complete shed.

Case research: Wheathaven Farm, Crediton, Devon

Installing two 183cm belt-pushed followers has decreased lameness, improved fertility and left beds drier at Wheathaven Farm, even within the winter months.

The milking cows’ cubicle shed is surrounded by buildings on the prevailing wind aspect, which limits airflow.

As a outcome, the Hosegood household began to see cows bunching at one finish of the shed.

In specific, two bays at one finish of the shed caught the prevailing wind and can be a lot cooler as a outcome.

Up to 100 cows can be crammed into these two bays, explains Ed Hosegood.

During a 30C spell in July final 12 months, cows had been clearly experiencing warmth stress, with milk dropping about 1.5 litres a cow a day.

That autumn, the household determined to set up two belt-pushed followers with directional fins underneath the steerage of CowPlan.

Ed Hosegood in shed

Ed Hosegood © Ed Hosegood

Farm information

  • Family farm run by Aubrey and Hazel Hosegood, their son, Ed, and daughter, Louise
  • 133ha (329 acres) farmed
  • 110 pedigree Holsteins housed and calving 12 months spherical
  • 10,500 litres a cow a 12 months at 4.33% fats and three.28% protein
  • Milked via two robots
  • Finishes all beef from the dairy
  • 300 Poll Dorset ewes

Choice of fan

Fans are situated 2.8m above the cubicle beds with a 30C angle from the horizontal. The air produced is sufficient to cowl two rows of cubicles.

The first fan is situated on the prevailing wind finish to draw clear air in and the second is within the center to push air down the shed.

The farm has single-section electrical energy reasonably than three-section, so inverters had been wanted to run the followers at a price of about £250 every.

Mr Hosegood selected belt followers over panel followers as a result of they had been greater, so fewer followers – and subsequently fewer inverters – can be wanted throughout the shed.

Fans in shed at Wheathaven Farm

© Ed Hosegood


The two followers price a complete of £4,300 + VAT, plus £1,400 + VAT for set up (together with inverters).

The followers are thermostatically managed. They come on at 8C and run at 20% of most velocity, and are on variable velocity till 18C. They then run at full velocity at 18C or above.

The working price within the winter is £300/month in electrical energy (at 15p/unit electrical energy). This is probably going to double in summer season. A 20kW photo voltaic array has been put in to energy the farm, together with the followers.

“They’re on practically all winter within the day,” says Mr Hosegood. “You’d be shocked once they come on. It’s very often 10-11C within the shed within the winter.”

Despite being put in within the winter months, he has seen some marked enhancements:

  • Less bunching – cows are extra evenly unfold within the constructing
  • Fewer sole ulcers – sole ulcers and bruising have decreased by at the least 30% owing to much less standing time
  • Improved fertility – in periods of warmth stress, Mr Hosegood noticed a rise in cystic cows. This had a unfavourable impact on being pregnant charges
  • Drier beds – as beds are drier, liming charges have decreased from twice to as soon as a day. Twelve-month mastitis charges now sit at 10.7 instances for each 100 cows, with solely three instances this 12 months.


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