Sheep in trees

By Pippa Geddes and Raimund Kohl

The breed is now used successfully by hundreds of tree growers and is especially popular with producers of Christmas trees. Provided that Shropshires are managed correctly, they are suitable for use in Spruce (Picea sp.), Pines (Pinus sp.) and Firs (Abies sp.), although the latter can sometimes be vulnerable to nibbling by sheep. Management techniques for ensuring that Shropshires work efficiently in plantations are available in a guide* published by the Shropshire Sheep Breeders’ Association of the UK.

Grazing Shropshires among fruit trees
Practical experience on many farms suggested that Shropshires were also suitable for grazing in deciduous plantations, including orchards of apples (Malus domestica) and pears (Pyrus communis). In addition to keeping weeds at bay, the sheep eat fallen leaves and so can help to prevent the spread of fungal diseases, such as apple scab (Venturia inaequalis). Mechanical removal of fallen scaby leaves is known to reduce the scab infection rate in spring (MacHardy, 1996). Reduction rates of 80% were reported from long-term experimental studies (Sutton and MacHardy, 1993).

Co-author of this article, Raimund Kohl, was instrumental in setting up a trial at the Research Centre for Fruit Growing at Lake Constance, Bavendorf, Germany to establish the suitability of Shropshires for use in commercial orchards. This trial started in 2006 and set out to monitor the performance and behaviour of Shropshire sheep in three different tree plots
(see table 1 below).

  Plot 1 Plot 2 Plot 3
Period grazed by Shropshire Sheep During full foliage ( May -June) During full foliage ( May -June) During leaf fall
Age of trees and type of root stock Older than 20 years, Middle high stem Planted in 1996, A2 Semi dwarf size Planted in 1987, M9 Dwarf size
Stem height above the ground (to lowest branches) Varies 70 to 85 cms 60 – 70 cms
Management system Very extensive No grass cut No chemical spraying Often mulched. Trees pruned in winter. No chemical spraying Organic apple orchard, sprayed frequently with permitted substances
Vegetation surrounding trees Old grass Fresh, young grass Grass cut very short and mulched

The trial showed that Shropshire sheep are suitable for use in orchards, however some management restrictions must be accepted. The following are the main conclusions of the trial:

Shropshire sheep were docile and easy to manage amongst the trees. Water and minerals had to be provided for them, but no additional adaptations, such as extra shelter, were required.
In all plots, sheep kept the ground vegetation tidy and short and routine mowing was not necessary. Nettles were not eaten, but Shropshires will consume them if they are cut and left to dry on the ground.
Under normal weather conditions, the grass sward remained in good condition whilst sheep were grazing. Shorter grazing periods may be required during exceptionally wet seasons.
Tree foliage in the growing season was attractive to the sheep. Leaves within reach were eaten, and the height to which tree foliage was consumed corresponded to the height of the sheep. In general, all branches to up to 1m above ground level were defoliated. The animals did not, however, rise on their hind legs to reach higher up. The amount of damage caused to the lower branches and soft shoots depended on the quantity and quality of other herbage on offer, and thus on the pasture management.
To minimise the tree damage, regulated management of the surrounding pasture is necessary. Sheep should not remain in the same area for longer than three weeks. Large plantations can be divided with electric fencing.
Thicker bark on older trees remained untouched by the sheep. Some damage was recorded in plots with younger trees. This was observed where herbage supply was short, and occurred only at the location where sheep rested. Compared with an earlier trial using Milk Sheep, the damage caused by Shropshires was insignificant and did not affect the long-term viability of the trees.
Use of sheep in orchards with strongly growing semi dwarf size root stock (for example: M25, MM106 and MM111) is recommended. With the standard root stock, M9, the leaf loss had too strong an impact on the nutrition of the tree.
Any spray treatments required by the trees must be carefully coordinated with the sheep grazing management. Disease resistant tree varieties which require a reduced spray programme are best suited to systems where sheep are utilised.
The very wet weather experienced during autumn 2006 made it impossible to ascertain if Shropshires eat fallen leaves. Leaves on the ground quickly become soggy and smeared with soil, making them unpalatable. Farmers elsewhere, who use Shropshires to graze farm orchards, report that the animals do consume dry, fallen leaves. Further research will be necessary to answer this question conclusively.
Environmental benefits
Groundwater monitoring programmes in catchment areas with considerable acreages under fruit and vegetable production show that many agrochemicals used to manage these crops have already reached the groundwater. For example, data is available from the Baden-Württemberg State Agency of Environmental Protection (LUBW) in Germany. Groundwater quality in the Baden-Württemberg state was monitored at 2,500 measuring points. Examination of 10 years’ data showed that 50 of the 86 controlled pesticides and five of the six metabolites were detected. For example, substances such as bentazon; dicamba; dichlorprop (2,4-DP); mecoprop (MCPP); diuron; glyphosate and terbuthylazin were detected. These had been used as herbicides and, in some cases, also for fruit crop production.

LUBW also introduced a special monitoring programme in 2006 to control tolyfluanoid (a fungicide used to control scab) and its metabolite N,N-dimethylsulphide (DMS). Some 56% of 101 measuring points recorded concentrations of DMS above the limit (0.1 µg/L). The highest number of polluted groundwater measuring points could be found in the main fruit and vegetable growing areas, such as the Lake Constance and Upper Rhine area.

Financial benefits
Environmental pollution and the growing market demand for “natural” food are the main reasons for lowering the use of agrochemicals and encouraging farmers to convert to organic farming systems. Shropshire sheep can play a major role in controlling the vegetation in fruit tree plantation and can, therefore, help to replace herbicides. However, farmers’ willingness to use sheep depends to a large extent on the cost-benefit, compared with a conventional system. The table 2 outlines the cost of controlling orchard herbage by mechanical means.

Table 2: Summary of the costs of controlling herbage between trees in one hectare of organic apple orchard

  Working hours (one person for one hour) Labour Cost (12GBP per hour) Cost of machine running costs and depreciation(GBP)
Mowing 6 times per year Tractor, 50kW, 2m mower 12 144 203
Root vole control 14 156
Leaf litter mulching with chaff cutter for scab control 4 48 68
Total costs (GBP per hectare) 619

Data are based on work by Stockert (1997) and KTBL Datensammlung ökologischer Obstbau (2005).

When stocked at a rate of between 6 and 10 animals per hectare, Shropshire sheep can replace the need for mowing, root vole control and, to some extent, scab control. The resulting cost savings amount to an estimated £619 per hectare. It is, however, good to mow at least once a year to ensure that any grassy areas not eaten by the sheep are cut short, and any remaining leaf litter will be shredded. The cost for one run with the mower is calculated at £58, and another 4 working man hours (£48) are necessary for some root vole control. So in total, the use of sheep can save around £500 per hectare per year.

To complete the cost-benefit comparison, one must take account the expense of managing the sheep, including labour, additional winter feed and the purchase of routine health-care. Set against these costs is the revenue obtained from lamb sales. In addition, fruit tree growers who market produce direct to the general public may find that Shropshire sheep can be used successfully to promote the “green” credentials of their businesses. Pollution-free production is a very attractive concept to today’s consumer.

Overall, the cost of keeping the sheep is roughly equivalent to the revenue from lamb sales. Thus a saving of £500 per hectare per year is the overall benefit of using sheep, in conjunction with the environmental bonus from having replaced the need for agrochemicals.

The additional workload of keeping sheep keeping is not very heavy and fits in well with the labour requirements of fruit production: The apple harvest in autumn coincides with the time when the sheep can be kept outside with minimal management requirements. On the other hand, the lambing period, which is the busiest time for sheep farmers, occurs in late winter when fruit trees require minimal management.

The future
Most Shropshires are currently used in Christmas tree plantations. But fruit growers are starting to take notice.
The results of the Lake Constance trial were published in 2007, and this has generated considerable new interest in Shropshires. French fruit producers made a joint importation of around 150 British Shropshires in summer 2008, and a repeat order for over 100 sheep was made in 2009. The breed society has received very positive reports of the performance of the sheep when grazed among a number of different fruit tree species, including use to control weeds in vineyards between the grape harvest and bud burst in the spring.
Operating figures show that the use of Shropshire sheep in commercial fruit cultures can be profitable, especially in organic farming systems. The breed society continues to gather technical information about the management of Shropshires in commercial fruit tree cultures, with a view to making this information more widely available to farmers and growers interested in this concept of environmentally friendly weed control.

Guide to grazing Shropshire sheep in tree plantations and vineyards

The second edition of a technical guide about grazing Shropshire sheep in tree plantations which was launched at Sheep 2008 from the Shropshire Sheep Breeders’ Association. The booklet has been significantly expanded since the first edition, published a number of years earlier, and now includes management advice from Christmas tree growers in Denmark, Germany, Switzerland and the UK, as well as new sections about the use of Shropshires in apple orchards and vineyards.
Entitled “Two Crops From One Acre” the guide provides all the practical information tree growers will need to assess the suitability of Shropshires for their plantations. It covers the different grazing systems developed for utilising Shropshires as the ultimate environmentally-friendly method of weed control plus information about recommended cover-crops, stocking rates and sheep selection.
The section about the use of Shropshires in commercial fruit tree cultures is based on a formal trial conducted in semi-dwarf orchards at the Centre for Fruit Tree Research at Lake Constance, Bavendorf, Germany. An additional use for Shropshires has also recently come to light, and the booklet includes a short section about the experiences of a French farmer who has successfully extended the use of his sheep from conifer plantations into vineyards.
“Most sheep are unsuitable for controlling herbage in tree plantations because they eat a lot of the foliage and cause serious damage by stripping bark. For reasons that remain a mystery, pure-bred Shropshires behave differently and they have a well-proven track record for controlling herbage on Christmas tree farms,” says Pippa Geddes, publicity officer of the Shropshire Sheep Breeders’ Association.
“Thousands of Shropshires are used by tree growers in Denmark, Germany, Austria and Switzerland, allowing them to significantly reduce the use of herbicides whilst producing a valuable second ‘crop’ from their land.
“The use of Shropshires in conifers was first developed around 20 years ago. Since then, practical experience on many farms suggested that the sheep could also be grazed in deciduous tree plantations, such as orchards. In this scenario, just as in conifer plantations, their use brings the benefit of environmentally-friendly herbage and weed control.”
A copy of this publication can be found in the Publications section of the website for downloading, hard copies can be ordered from the Society Secretary by sending a Stamped Addressed Envelope with 96p postage to – Simon Mackay, SSBA Secretary, 146 Chandlers Way, Sutton Manor, St.Helens, Merseyside, WA9 4TG.
For more information about the Shropshire Sheep Breeders Association please contact The Secretary, Simon Mackay on UK (0)1744 811124
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