A few simple adjustments to the design of cattle housing can make a dramatic difference to cow welfare and productivity. Jamie Robertson, research fellow at Aberdeen University, points out where changes can be made.

Half of all cattle buildings - old and new - are not fully fit for purpose, increasing the risk of sickness and poor production. Before housing cattle, livestock producers should reassess their sheds and make some key changes to improve cow comfort and productivity. Big steps can be taken, even with older units, to improve the indoor environment with reasonable outlay.

Why are buildings an issue?

Despite years of conclusive research on building design, many new cattle sheds are still being incorrectly built. The contribution of poor building design to illness is considerable, and it is something that people can change. It is important to consider cattle housing from the cows' point of view, and not simply opt for the first building that fits within planning and financial parameters.

Equally, farmers with older units can reassess a building's design, and make some simple, and relatively cheap, changes to improve it. In doing so, they could dramatically improve cattle health, welfare and productivity.

The main problem found with both old and new buildings is inadequate moisture control through ventilation and drainage. A cow produces 35-45 litres of urine and faeces as well as 10 litres of moist air through respiration every day, and when it is not quickly channelled away cattle are at increased risk of mastitis, foot problems, pneumonia and other diseases.

What can you do to improve the drainage?

One of the simplest methods of reducing moisture in and around cattle housing is to clean and repair downpipes and gutters.

Few buildings' drainpipes are fully maintained, but it is a quick and cheap autumn job which can save up to five days' labour by keeping rainwater out of the slurry system.

Within housing and yards, consider creating channels in existing floors, or installing a new floor with the correct slope and drainage to prevent puddles from forming.

Ensure drainage around water troughs and calf milking machines is adequate, and work with the natural gradients to make life easier.

Where loose housed stock are wet underfoot, look at the drainage underneath the bedding - if it is not working, take action. Part of the secret to keeping any animal healthy and productive is a dry environment.

Where air or bedding is damp the risk of chronic health problems increases, as warm, moist conditions are ideal for viruses and bacteria to thrive.

What about ventilation?

It is essential to provide an exit for warm, damp air at the top of the building.

There are two key aspects to a well ventilated building - intake of fresh air and outlet of warm, damp air.

With 100 cows breathing 1t of moisture into the air every day, it is essential to provide an exit at the top of the building, where warm air naturally rises.

As a guide, every calf weighing up to 125kg needs 0.04sq m of ventilation outlet in the roof, while growing and adult cattle typically need at least a 200mm gap along the full length of the ridge. Pay attention to detail - a few millimeetres too little can make a huge difference to the air flow.

Ideally, create ridge openings over passageways to prevent rain falling onto bedding. In high rainfall areas producers may consider an open, covered ridge, but allowing large amounts of moist air out of the building is far more valuable than preventing small amounts of rainfall from coming in.

Air intake areas should be at least double that of the outlet, and evenly spread around the house to prevent corners of stale air. Where buildings are open on one side, ventilation inlets will still be needed on the other walls, otherwise air will not circulate properly.

Won't the shed be draughty?

A smoke test can help you assess airflow through the building.

The golden rule is to have a solid wall equal to the animals' height, to prevent draughts at body level, which will drain their energy. In existing buildings, consider pushing the wall sheet out above the base wall, to create a horizontal inlet. Another option is to install space or Yorkshire boarding - but don't leave a vertical gap larger than 1in as it will channel wind and rain through.

Perforated sheets are a good alternative for exposed sides of the building, but make sure 10-12% of the area is voided, or ventilation may not be sufficient. In buildings with open sides or large gateways, create a windbreak at least up to the cows' height. South facing sides could benefit from perforated blinds, which allow light and fresh air in, but control draughts and can be removed when not required.

Large buildings, or those in sheltered areas, may struggle to circulate enough air, so install fans with vented tubes to blow fresh air through the building, or fans hung from the purlins every 60-80ft to remove heat and moist air.

Producers with buildings that cannot be readily altered should consider their other options. Maybe they have a machinery store which would be more suited to cattle housing. Where poorer buildings have to be used, stock them with the least vulnerable groups like growing stores and heifers, not calves or dry cows.

What about building layout and cubicles?

Any new building should be designed according to the number and type of animals to be housed, but also consider the machinery you want to use in it, and the flow of cattle through it. Try to avoid blind alleys, sharp corners and dark spots. Be generous with water troughs and feeding space to account for hierarchies, or timid cows will never do well.

Cubicles are cow-specific, and should be designed or altered according to your cows' size. Many older cubicles are too small for modern breeds, leading to rubbed hocks, lesions, and cattle lying in passageways. Lunge space is important - get rid of solid fronts and install cables instead. If you have enough passage width, put in a curb to extend the cubicle length, and if the step is too high, raise the floor.

Older floors often get cracked and worn - these will both harbour disease and lead to cows slipping, potentially resulting in permanent injuries. Cracked floors need to be re-skimmed, while worn floors can be acid-etched or ground out. Consider cow comfort and improve drainage at the same time - it is considerably cheaper than a new building.

Is bedding choice important?

Bedding should always be clean, dry and non-dusty - but the type used is usually a financial decision. Mattresses can be a good way to extend the life of older cubicles, and sand is a hygienic option. Store bedding in dry areas, and use second-rate supplies for low-risk animals.

In loose houses bedding is an essential part of the moisture interaction. Keep eating and lying areas separate so that bedding remains dry - and if you are short of straw, consider using oilseed rape straw or other alternatives underneath the top layer.

The key to all good building design or modification is to look at cattle behaviour and change the housing to meet their needs. Are they lying in clean, comfortable areas - if not, why not? Perhaps they are huddling together or avoiding part of the building - maybe it is too draughty, or dark, or damp and stale. By providing the right level of ventilation in dry and comfortable surroundings, you can significantly improve your cows' health and welfare, and your bottom line with it.

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Golden rules

• Target management of moisture - consider the passage of slurry, water, and damp air
• Get fresh air to all your stock - it's free, and the best bactericide and virucide we have
• Control air speed at animal height - draughts can cause significant physiological stress, especially to calves