Short of winter housing for sheep? Polytunnels could be the answer. Angela Calvert reports.
Advancements in structural design, developments in covering materials and improved engineering techniques make them a credible, inexpensive alternative to traditional livestock buildings.
They are increasingly being used on greenfield sites or where additional accommodation is needed quickly and cheaply, and often on rented land where the tenant is not prepared to invest expensive buildings on property they do not own.
Polytunnels are easily and quickly constructed and can range from single span to larger multi-span builds. They allow light and warmth into the building which can improve feed conversion rates, but also creates healthy, dry environments which are less favourable to bacteria and fungi than traditional buildings and can reduce bedding costs.
Nigel Carr from Northern Polytunnels says: “We have seen a huge increase in sales in recent years, not only from farmers wanting them for lambing, but using them as longer term winter housing as we seem to be experiencing wetter winters and it is advantageous to get stock off the land for longer periods.
“They are also useful for hay and general storage and a dry place to house sheep before and during shearing, making them more of a year-round investment.
“They are becoming popular as calf housing and poultry sheds as well as for cattle, goats and pigs.
“Obviously, there are some advantages to conventional buildings which have greater height and are a stronger structure, but polytunnels can provide an ideal environment for stock at a fraction of the price.”
Polytunnels can be erected on most surfaces. Sometimes they are put onto a hardcore base, but they can also go directly onto a field. Steel tubes are set in concrete as foundations.
The tubular steel hoops slot over the foundation tubes to create the main framework and a polythene cover is then stretched over the hoops.
The greater the amount of steel, the stronger the structure. So sometimes it is wiser to opt for closer hoop spacings.
The height of the sides is increased in relation to the width of the tunnel which can range from 5.5 metres (18ft) wide to 9.14m (30ft).
The wider the tunnel, the lower the cost per square metre, making the 9.14m (30ft) one the most economic.
If a central feed/access passage is being incorporated into the layout design, then the percentage of ‘lost’ housing space is vastly reduced with wider structures.
Single span structures usually offer higher levels of ventilation, due to the ratio of vented sides to floor space.
Multi-span tunnels are ideal for housing larger flocks and can be linked by additional feeding passageways which allows access for small machinery, making feeding and bedding easier.
Mr Carr says: “The structure should be erected on the most level site you can find, although a slight slope is not a problem. If the area is wet land, drains can be put in or it can be raised up on hardcore.
“Construction is quick, typically three days for a 9.14m (30ft) by 45.72m (150ft) structure, the only constraint being the polythene has to be put on on a calm day with little or no wind, so this can sometimes hold things up for a few days.”
Jeff Aiken is flock manager for Procters Farm’s pedigree Texel flock at Tatham Hall Farm, Wennington, Lancashire, lambing 200 ewes.
Mr Aiken says: “When my boss added this farm to his business for sheep, which had previously been run alongside the cattle enterprise on another farm, there were insufficient buildings for lambing.
“We did not want to rush into putting up sheds until we knew what we really wanted, so we opted for polytunnels. But I have worked with them before and really like them so am happy to keep them permanently.”
They have a multi-span structure with feeding passageways which has walkways running horizontally across it, so it is not necessary to go outside to access all the sheep and they can be moved around easily.
Mr Aiken says: “It is a really good environment for lambing and sheep seem to really like them and do well. They let in a lot of light and they are warm in winter, but at the same time are well ventilated. This set up works really well at lambing time, as it is all under one roof.
“My only criticism is they can get warm if it is a hot summer and there are a lot of sheep in them, but summer is not a time when we need to use them for a large number of sheep so this is not a major problem.”
Bart and Elaine Marsden farm with their sons Nat and Roger in West Bradfield, Ribble Valley, Lancashire. They run suckler cows, 250 milking sheep and about 700 commercial ewes.
They erected two single 9.14m (30ft) by 27.42m (90ft) polytunnels prior to lambing last year.
Mr Marsden says: “We lost the use of a rented farm where we had previously lambed the commercial ewes and had insufficient buildings at another farm we rent and did not want to invest in a conventional build on a farm we did not own, especially as we do not need it all-year-round.
“We did have some initial problems with the local authority regarding planning as we are in an area of outstanding natural beauty, but these were resolved on the condition that we used green polythene which would blend in with the landscape.
“But we are really pleased with how the polytunnels have helped. Sheep seem really happy in them and do very well. As well as for lambing, we have used them to fatten lambs.