Building designs have improved markedly in recent years, yet many farmers are still getting it wrong. Olivia Cooper finds out why.
Livestock buildings play a critical role in stock health – but more than half of them are not fit for purpose. Even new buildings are being incorrectly built, leading to poor growth rates and disease, according to Jamie Robertson, research fellow at Aberdeen University. However, with a few simple changes farmers can dramatically improve their cows’ environment, whether working with new buildings or old.
The two main mistakes that farmers make are providing too much ventilation – leading to chilled cattle and poor growth rates – or too little, resulting in a higher chance of respiratory disease.
“We have a difficult situation in this country due to our windy and wet climate – it often leads to a crude approach to building design,” says Mr Robertson. “In windy areas people tend not to have any ventilation, and in other areas they leave big gaps above gates, for example, which increase the wind speed through the building and allow ingress of water. We don’t want water in our buildings, and straw is too expensive to throw rainwater at.”
Many older sheds are clad in Yorkshire boarding or space boarding, with transparent roof lights to let in daylight. However, this often leads to hotspots in the building, as well as dark corners. The space between some wall claddings also lets air flow into the building in ‘knife blade’ form, creating draughts and allowing wind and rain to travel a long way into the shed, so gaps must not be any larger than 1”.
Surprisingly, many new builds have a similar problem. “There’s a fashion for big tall buildings with no walls, which is great in the middle of June but hopeless in this climate for the rest of the year – it’s a disaster. It’s a great shame that, despite years of conclusive research on building design, brand new buildings are going up that won’t ventilate properly – it’s a complete waste of money.”
Wind speed will do the most damage to youngstock, by lowering their temperature, which has a direct line to their immune competence, he adds. “For older stock it will reduce their feed conversion efficiency as they may have to use energy to stay warm.”
Providing a constant supply of clean, fresh air is closely linked to higher levels of productivity, as demonstrated by the pig and poultry industries. “If you have inadequate ventilation you are creating a warm and moist environment, which is supportive of many bacteria and viruses, and prolongs the survival of a number of important pathogens.”
Livestock buildings should always have a solid wall up to the animals’ height, to prevent draughts at body level, says Mr Robertson. “If you feed around the outside of a building or have large gateways, create a windbreak beyond them.” Above the cows’ height, the walls should be vented to allow airflow in, with a hole in the roof to let warm, moist air out.
The ventilation area should be calculated according to the stocking rate, age, size and performance of cattle, as it varies according to their metabolic rate. “Getting it right means the animal is not immune stressed as a result of its environment, and will be able to fight off a lot more disease as a result. The building is only part of stock management, but it’s the easiest to understand because it doesn’t change on a daily basis.”
As a guide, every calf weighing up to 100kg needs 0.04sq metres 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 mm too little can make a huge difference to the air flow. The air intake area should be at least double and ideally four times 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.”
Large buildings, or those in sheltered areas, may struggle to circulate enough air, so farmers could install fans with vented tubes to blow fresh air through the building, or hang fans from the purlins every 60-80ft to remove heat and moist air.
In older sheds, it is possible to push the wall sheet out above the base wall, to create a horizontal inlet. But an ideal solution is to install perforated or mesh products, adds Mr Robertson. “I think we need a lot more perforated products in our cattle buildings – they allow air in, but reduce wind speed and don’t let the rain through like space boarding can. However, you need an adequate inlet area, so 25% of the sheet should be voided – some products are only 4.5% voided, which is totally inadequate.”
One relatively new option is a perforated metal sheet called Highlight, which provides excellent ventilation and light transmission, negating the need for roof lights. Manufactured by United Roofing Products in Devon, the galvanised steel cladding contains a 25% perforated area, but in the form of tiny holes which allow light and air through, but not the rain.
“If I had my way, every cattle building in the country would have mesh products on the sides. Unfortunately, the agriculture industry isn’t well suited to floppy fabrics – if it comes loose and is not maintained it can be ripped to shreds,” says Mr Robertson. “The Highlight sheeting is suitable because it’s a lot more durable and is very easy to fit. It is also good for general and dual purpose buildings, as it doesn’t let birds in, and means you won’t need to use lots of electricity for lighting.”
The key to all good building design is to look at cattle behaviour and change the housing to meet their needs, he adds. “Are the cattle evenly spread throughout the shed, or are they avoiding particular areas which are dark, draughty, damp or stale? Designs should be individually tailored to provide the correct level of protection and air access around the building, which might mean no cladding on a well protected side, Highlight on another two sides, and Galebreaker on a fourth. By getting it right, producers can significantly improve their cows’ health and welfare, and profitability with it.”
Colin Grabham and his son Peter have been using Highlight perforated sheets on their cattle sheds at Watton Farm, Halberton, Devon, since 2002. “We started with just one shed and found it so good that we’ve since put it on two more buildings, including on three sides of a 90×45 foot barn,” says Colin. The family sell beef locally from 100 Limousin x and Longhorn suckler cows, which are grazed during the summer and loose housed with youngstock on straw over the winter.
“It’s brilliant – there’s plenty of light and air, and the dust doesn’t stick to it like wooden boarding,” he adds. “When you’re blowing straw in, it doesn’t stick to the metal at all, so it’s much cleaner – and the holes don’t clog up like other perforated products.”
They have also noticed considerable health benefits. “We have hardly had any pneumonia since we installed it – the buildings are much lighter and airier. It’s like standing in fresh air, but you don’t get wet if it rains or snows – and it keeps the birds out,” says Peter. “You don’t need any lights – and you can see straight through to the outside. It’s definitely a better working environment and healthier for the cows. Wooden boards can harbour more bugs than metal, and as we continue to replace boarding with the Highlight, the cows’ health is getting better and better.”
The sheds all have raised ridges to allow air flow out, but with Highlight there is no need for roof lights, preventing the risk of hot spots and dark areas. “It is a bit more expensive than space boarding, but it hasn’t rusted and it’s very easy and light to put up. If we were putting another building up we would definitely use it – the benefits of extra light and better health mean it pays for itself pretty quickly.”