Outwintering cattle on woodchip pads offers many benefits including improved animal health and welfare, less pasture damage, reduced labour costs and a cheaper alternative to putting up buildings.
Why should I use an out-wintering woodchip system?
Woodchip pads can be used to facilitate early spring and late autumn grazing where there is a risk of pasture damage. Alternatively they can be used as a cheaper alternative to putting up sheds to house stock over winter. The pad could allow stock access to self feed silage, or one side of the pad can be designed to include a concrete stance and feed barrier. Woodchip pads for use as an outwintering area has been of interest to livestock farmers for a while. However the early pads did not contain the drainage from the corrals and as such presented a risk of pollution to ground and surface water. This material has been taken from a LINK project on Sustainable Livestock Production, looking at the impact of designing and managing woodchip pads, the effect on animal performance and the risks to the environment.
Top tips
- Seek specialist advice when you start designing the pad.
- The ideal site is gently sloping and south facing, away from public view with easy access to off-pad yard areas or a grass paddock.
- Most nutrients remain within the surface layers of woodchip. Only 5-10% of the Nitrogen and phosphate excreted is contained in the effluent that drains from the pad.
- Research has shown that much of the rainfall and excreta is absorbed by the woodchip. There are also losses through evaporation from the pad surface.
- To drain pads the recommendation is to use perforated plastic piping of a minimum 80mm diameter located in shallow trenches with a minimum fall of 2%.
- Coarse woodchips (5-10cm) encourage rapid drainage and a clean pad surface. However for animal welfare purposes, fine chips are better. A good compromise is a 30cm base layer of coarse chip with a 20cm surface layer of fine material.
- It is essential to actively manage the pad, especially in difficult weather conditions, for example freezing or very dry conditions followed by heavy rain.
- The use of cultivators to alleviate heavy surface soiling is generally not successful. Heavily soiled chip is best removed and replaced with clean chip.
- To make the best use of the available N content, apply dirty woodchip direct to grassland. Fine chips will become incorporated into the sward in a few weeks. Coarse chips however are not suitable for applying to grassland.
- To minimise dunging on the woodchip it is a good idea to located feed fences and water troughs outside the pad area on a concrete standing.
Key features
Click on the area that you are interested in to find out more about different aspects of designing, and managing woodchip pads.
Planning and installation
The development of a woodchip pad on-farm requires an application to be made to the local authority.
What are the planning requirements?
Depending on your individual farm circumstances it will mean either a Prior Notification under part 6 of Schedule 2 to the Town and Country Planning Act (General Permitted Development) Order 1995 or a full planning application.
TAKE NOTE: Planning criteria are subject to change. Check your situation with your Local Authority before starting to build.
Prior notification
The main advantage of this type of application is (subject to the criteria below being fulfilled) Local Authorities can only consider the plans on their design and siting.
Criteria
- The farming unit must be in excess of 5ha
- The floor area of the pad must not exceed 465m2
- The pad should not be within 25m of a metalled highway
- Any development involving the accommodation of livestock or farm waste should not be within 400m of a non- agricultural dwelling.
- Siting and design has to be justified and positioned to have minimal effects on the landscape.
Full planning application
Unlike the option above, for a full planning application there are no set criteria that need to be fulfilled. However by going for a Full Planning Application, any plans are then assessed against planning policy and are available for comment from bodies like the Highways Agency, Environmental Health, the Environment Agency and Conservation or Ecological Officers.
The points below are key when addressing policies for planning applications:
- Consider the justification for the pad. For example why is the proposal required in terms of the needs of the holding as well as why it has been designed and sized as it has.
- Consider the reasons why the proposed site has been chosen. Best practice is to site structures adjacent to existing buildings to reduce any impact on the landscape.
These points need to be addressed in a Design and Access statement (a statutory document) that is submitted as part of the Planning Application form known as a 1APP. Along with correctly scaled drawings, supplementary reports may also be needed, for example, a Landscape Assessment and an Ecological report.
Cost implications
Recent costs (Nix, 2011) estimated that covered straw yard cattle housing (allowing 4m2 per animal) at £700 per head, and a slatted floor building for 120 growing cattle (1.7m2 per animal) at £1400 per head.
A scoping study of woodchip pads in 2005 estimated that the construction costs (excluding on-farm labour) averaged £106 per cow.
It is a good idea to list the individual components needed to build a woodchip pad to work out potential installation costs. The table below can help to breakdown these costs and give guide figures.
How much does it cost to install a woodchip pad?
Recent costs (Nix, 2011) estimated that covered straw yard cattle housing (allowing 4m2 per animal) at £700 per head, and a slatted floor building for 120 growing cattle (1.7m2 per animal) at £1400 per head.
A scoping study of woodchip pads in 2005 estimated that the construction costs (excluding on-farm labour) averaged £106 per cow.
It is a good idea to list the individual components needed to build a woodchip pad to work out potential installation costs. The table below can help to breakdown these costs and give guide figures.
Guideline summary of costs for the construction of a woodchip pad system
Click here (PDF) to access the table of guideline costs for constructing a woodchip pad system.
These figures relate to the Midlands of the UK.
Cost variations
Cost savings can be made according to local opportunities. These may include a cheap source of chipped wood, or highway crash barrier steel for fencing. If your site has low permeability subsoil, costs are likely to be reduced dramatically as there will not be a need for an impermeable base lining.
Depending on the design, costs have been estimated to vary between £190/hd to £550/hd for a woodchip pad sufficient for 100 beef cattle, assuming 10m2/hd space allowances. These costs do not include the cost of effluent storage.
Source: Materials and images adapted from “Improved design and management of woodchip pads for sustainable out-wintering of livestock” compiled by Project Consortium Partners including Jessica Buss (BGS), David Chadwick (North Wyke), Lynfa Davies (HCC), Ken Smith (ADAS), and Mary Vickers (EBLEX).
Design and construction of woodchip pads
In designing a woodchip pad, site selection is crucial. Site selection will impact on many aspects of design and construction as well as pad management.
Pad design
Things to consider
Apart from any siting issues relevant to planning applications, the following points are worth looking at carefully.
- Site exposure – where possible select a sunny, south facing area without shade, but open to winds to promote surface drying. Try to avoid areas with large trees and walls close to one side which will tend to result in muck overload hotspots.
- Shelter – exposure to extreme cold winds and wet conditions can be a problem. The use of shelter such as windbreak material or a hedge can be beneficial for the welfare of less hardy breeds.
- Public view – It is important to make sure that you locate the pad away from public view. Poor perception of animals on woodchip can lead to problems.
- Land drainage – Avoid areas that will compromise drainage, these may include low-lying sites which could flood and would prevent adequate depth of outfall for the drainage system, areas with springs or seepage lines upslope or beneath the site, and areas with rocky subsoil.
- There should be no land drainage systems within at least 10m of an outwintering pad.
- Proximity to water courses and water supplies – Site the pad at least 50m from a watercourse or ditch, and from any drinking water supplies. Also make sure to avoid sensitive groundwater areas (where risks have been identified by the Environment Agency).
- Sloping ground – Areas with steep slopes complicate and increase the amount of work needed to prepare the site as it is then necessary to undertake excavation and ground contouring (which will increase costs). Gentle slopes of between 2-3 degrees are ideal, as they will allow gravity drainage of effluent to store down-slope of the pad.
- Field access – during extended periods of freezing weather, it is necessary to have an area to remove the stock to, either in the form of an off-pad yard area or grass paddocks.
- Access to feed – Close access to silage or other feed facilities will minimise the work needed for stock feeding.
How should I design the pad?
Base your pad size on the type of stock, the number of animals being kept on it, the minimum space requirements (see the table below) and whether you are feeding on or off-pad.
| Minimum space requirements per animal (m2) | ||
|---|---|---|
| Animal Type | On pad feeding | Off pad feeding |
| Dairy cow | 18 | 12 |
| Suckler cow | 16 | 10 |
| Beef cattle (>2 years) | 16 | 10 |
| Cattle (1-2 years) | 12 | 8 |
| Cattle (<1 year) | 10 | 6 |
Table source: Department of Agriculture, Fisheries and Food, Eire
If the animals are to have access to sheltered yard areas or will only spend part of their time on the pad then the space requirements can be decreased. Previous trials have shown that animals that have free access to both an outside woodchip pad and sheltered housing will spend most of their time outside on the pad.
It is essential when designing the pad to consider effluent collection. It is essential that it is collected via a properly constructed drainage system. On heavy clay soils this may or may not require compacting with a roller to provide an impermeable layer that is at least 1m thick. Where there is a different soil type, an impermeable liner is required. A 5cm layer of sand below and 20cm of subsoil above the liner will protect the integrity of the membrane.
Construction
Drainage systems
This should comprise a minimum 80mm diameter perforated plastic pipe, installed at a maximum of 3m centres, in trenches or at the base of sub-soil ridges, with a fall of at least 2%. This will minimise costs as stone is not required across the whole pad area only above the pipe work. See the diagram below
Insert diagram
These drainage pipes should then drain to a 100mm diameter perforated plastic collector drain at the outfall. Another option is a permeable backfill stone layer of about 20cm depth to cover the pipe.
Insert other diagram
It is a good idea to have external access to the drainage system which will allow jetting clearance of any blockages with solids within the pipes from the woodchip or slurry. To prevent this, one option is to put a coarse geo-textile membrane above the drainage stone to prevent the ingress of solids
Effluent drainage from the pad
It is essential to calculate the effluent production from the pad and also from any slurry collected from concrete feeding areas. As under NVZ regs the effluent is classified as slurry the NVZ rules apply in terms of storage.
In order to estimate effluent volumes and amount of slurry that will be collected on concrete areas, the daily deposition of dung and urine must be calculated for the time the animals will spend on the pad. These can be based on standard values that are in the table below.
Table – Standards for daily excretal output for cattle.
Research has shown that cattle spend approximately 33% of their time on the feed race and 66% of the woodchip pad. The woodchip pad will absorb some of the effluent. Research has shown that for a 1000m3 pad, this reduction in effluent volume would amount to around 8m3 per week, or 1700 gallons.
How much woodchip will I need?
Spreading woodchip should be done carefully so as not to undo all construction of the drainage system. Begin spreading from the edger allowing the loader to work on the spread chip. For best results and to avoid wheelings; chip directly onto the pad.
The recommended depth of woodchips has changed from early guidelines. Experience in the UK has shown that a minimum of 0.4m is advisable, which will allow protection of the drainage network if machinery enters to clear dirty surface layers.
It may be possible to source woodchips as sawmill by-products. However there are regulations concerning the use of recycled timber (for example off-cuts or joinery / manufacture surplus). The Environment Agency has issued a position statement, to read it click here.
Where waste wood is being used, ensure that all contaminants (for example wire and nails) are removed. It must not be mixed with other materials for example plasterboard, plastic, metal, cabling or MDF. If there is any doubt as to the suitability, contact the Environment Agency.
Farmers will require a waste exemption to use untreated waste wood. A U8 exemption has to be registered before use. For more information please click here.
Size of woodchip
In terms of animal welfare, finer woodchip seems to be better. However this does retain more dung solids and may result in dirtier animals. This greater retention of dung by the finer chip may mean that the drainage system will be kept clear and thereby reduce the nutrient loading of the effluent.
A good compromise seems to be a fine chip surface layer with coarse chip underneath, which allows comfort for the animals and ease of removal when the solids build up.
Pictures
Feeding systems
Feeding and watering systems can be either on or off-pad. However research has shown that siting these off the pad will reduce dunging on the pad and any potential slurry hotspots. It will also reduce the need for removal of soiled material.
It is good practice to use concrete feed areas, designed to allow regular access for scraping off the slurry. To help keep the slurry off the pad, it is a good idea to have a step up or down to the woodchip pad and also at the feed barrier to prevent contamination.
The feed stance should be wide enough to accommodate all the animals feeding at one time, and deep enough to take the whole animal without it fouling the woodchip area behind it.
Water supply pipes should be lagged for cold periods.
Key points to remember
Pads do not manage themselves
The surface must be actively managed. Heavily soiled, wet areas need to be cleaned off and if necessary the chips replaced.
Attempts to clear heavily soiled chip pads with cultivators have given little success. Stock can be moved to one side whilst maintenance takes place, they do not need to be housed.
Source: Materials and images adapted from “Improved design and management of woodchip pads for sustainable out-wintering of livestock” compiled by Project Consortium Partners including Jessica Buss (BGS), David Chadwick (North Wyke), Lynfa Davies (HCC), Ken Smith (ADAS), and Mary Vickers (EBLEX).
Stocking rates, health and welfare
The management of the pad impacts directly on the viability and operation of the system and its efficiency.
How many is the right number?
Sensible stocking rates will depend on the intensity of use of the pad, the length of time that the animals will be kept on the pad and the feeding arrangements.
Feeding animals on the pad will reduce the potential stocking rates as the slurry solids loading rate will increase.
Studies have shown that allowing an increased area per animal has resulted in faster growth rates in cattle weighing between 470-670kg LW. However even at the tightest stocking density (see table below) there was still acceptable animal performance.
Stocking rates for woodchip pads
| Area allowance (m2/animal) | 11.8 | 14 | 18.6 |
| Growth rate (kg/hd/day) | 1.20 | 1.39 | 1.40 |
Table source: Impact of area allowance on cattle growth rate in research at North Wyke, Devon
Slurry hotspot areas
Woodchip pads most often fail due to rapid accumulation of slurry solids. A prolonged dry spell followed by heavy rain can often cause problems with surface accumulation of slurry.
In prolonged freezing conditions animals must be removed from the pad as the drainage will be impeded and there is high risk of run off and environmental pollution. If animals remain on a frozen pad it is likely to become very dirty and soiled and need clearing after the thaw.
Some or all of the top layer of soiled chips should be removed and replaced with new chips. The number of times that this will need doing will vary depending on stocking rate and pad design.
Woodchip pads for dairy cattle
Pads are a common feature in NZ and France but are not so common in the UK or France. They can be used for heifers and dry cows, and also milking cows where they also have access to daytime grazing. Pads have also successfully been used for calving, however this does rely on low stocking rates and good management.
Woodchip pads for beef cattle
This type of system is particularly suitable for growing cattle and dry or lactating suckler cows. Research from Ireland has shown that overwintering on woodchip pads has improved daily liveweight gain and feed conversion compared to those housed conventionally.
| OWP | OWP + Slats1 | Slats | Straw | |
| Space allowance (m2/head) | 18.0 | 17.5 | 2.5 | 4.0 |
| Feed Intake (kg DM/day) | 10.88 | 10.58 | 9.50 | 9.79 |
| Liveweight gain (kg/day) | 1.40 | 1.33 | 1.01 | 1.10 |
| Feed conversion (kgDM/kgLW) | 7.77 | 7.95 | 9.41 | 8.90 |
Effect of wintering systems on finishing cattle performance. 1Slats at 2.5m2 per cow with free access to OWP at 15m2 per cow. Source: P French, TEAGASC, Moorepark Research Centre, Fermoy.
Woodchip pads for sheep
Very little research has been undertaken for the use of pads with sheep. Indoor tests with woodchip bedding has shown that a clean surface reduces the risk of infection to new born lambs, however the sheep were sensitive to feet bruising from irregular sharp chips. Scottish research suggests an area of 3m2 per animal for adult sheep.
Animal Health and Welfare
Well managed woodchip pads provide an environment in which cattle thrive and health and welfare can be better than in other types of accommodation.
Where do cattle prefer to be housed?
Research carried out in Ireland has shown that when cattle are given a choice, they will prefer to be outside on a pad rather than in a shed. Alongside this conclusion it has also been observed that if cattle are used to being inside bedded on straw, they require some time to “acclimatise” to the change in environment, and may become dirty initially.
Health benefits
Irish trials have shown in dairy and beef cattle that there is a marked reduction in respiratory problems (for example pneumonia) as well as lameness and foot problems.
However there has also been shown to be an increase in the level of mastitis if the pad is not correctly managed, and if muck is allowed to accumulate.
Feeding is best managed off-pad in a concrete area which can be easily cleaned. This will make sure that animals are not exposed to excessive levels of wet manure which can increase levels of dermatitis and heel erosion and make the animals dirtier.
Managing lameness and mastitis
| Don’t | Do | |
| Lameness | Don’t use very large chip greater than 50mm across
Don’t expose cattle to excessive amounts of wet manure, which can cause dermatitis and heel erosion |
Ensure that the feed area is scraped regularly and has an inner and outer kerb / lip to minimise muck spreading into the pad or onto the feed
Allow cattle previously housed on other systems time to acclimatise |
| Mastitis | Don’t let muck accumulate on the pads to an extent that cattle are unacceptably dirty | Regularly replace the top layer of chips to ensure cows do not get their udders excessively dirty. |
Table – Do’s and Don’ts regarding lameness and mastitis on OWP’s.
It has also been discovered that cattle housed on woodchip pads are able to maintain their body temperature through activity in the rumen ( as long as they are well grown and fed appropriately), and as such are not environmentally stressed
Animal performance
Animal performance data is summarised in the table below, and showed a consistent trend towards daily liveweight and carcass gain.
| Conditions | Exposed OWP | Sheltered OWP | Slatted house | ||||
|---|---|---|---|---|---|---|---|
| Space allowance (m2) | 6 | 12 | 18 | 6 | 12 | 18 | 3 |
| Liveweight Gain (kg/day) | 1.17 | 1.17 | 1.22 | 1.17 | 1.14 | 1.23 | 0.99 |
| Carcass gain (kg/day) | 0.69 | 0.70 | 0.71 | 0.66 | 0.66 | 0.73 | 0.62 |
| Feed intake (kg DM/day) | 9.92 | 10.01 | 10.22 | 9.85 | 10.08 | 10.06 | 9.64 |
| Feed efficiency (g carcass gain/kg & DM intake) | 57.7 | 57.7 | 57.3 | 54.3 | 53.3 | 60.7 | 51.3 |
Table: Animal performance, carcass characteristics and feed efficiency of finshing steers (474kg initial liveweight), out-wintered on woodchip pads at different stocking densities, with or without shelter, relative to indoor housing on slats.
Looking at the animal’s ability to cope outside in the climatic conditions, results showed that on no occasion did the climatic energy demand (energy that the animals require to keep warm) exceed the energy released due to feed digestion. Animals housed outside showed some level of adaptation to the conditions by increasing hair length.
Source: Materials and images adapted from “Improved design and management of woodchip pads for sustainable out-wintering of livestock” compiled by Project Consortium Partners including Jessica Buss (BGS), David Chadwick (North Wyke), Lynfa Davies (HCC), Ken Smith (ADAS), and Mary Vickers (EBLEX).
Environmental risks and management of soiled woodchip
Well designed and managed woodchip pads can help reduce the environmental emissions associated with cattle production.
Woodchip effluent
The SSAFO regulations classify effluent generated from woodchip pads as slurry, with significant implications regarding its storage.
Any new, substantially reconstructed, or substantially enlarged slurry storage facilities must comply with the SSAFO regulations and in conjunction with any other storage must provide four months slurry storage capacity on the farm.
You need to notify the Environment Agency at least 14 days before any such store is first used. However it is a good idea to seek advice from the Environment Agency at an early stage of pad design to ensure that what you are planning will meet the current standards. As mentioned previously, as woodchip effluent is classified as a slurry, if your farm is in an NVZ then normal NVZ regulations apply concerning storage and closed periods for spreading.
Research has shown that effluent produced from woodchip pads is consistent with or of lower polluting potential that the published figures for dirty water and as such much below those expected in slurries. Click here to see the table.
The analysis has shown that more than 90% of the input N and P is retained within the solids built up on top of the woodchip pad. This material, when analysed is similar to FYM. See table
| Samples | DM% | Total N (kg/t) | NH4-N (kg/t) | P2O5 (kg/t) | K2O (kg/t) | Bulk Density (t/m3) | |
| Brecon | (4) | 31.6 | 2.6 | 0.03 | 0.6 | 1.2 | 0.87 |
| Coalville | (9) | 31.4 | 1.9 | 0.24 | 2.2 | 1.3 | 0.97 |
| Bedding chip (Pwllpeiran)1 | (3) | 36.6 | 1.2 | 0.04 | 1.6 | 4.5 | – |
| Cattle FYM2 | – | 25.0 | 6.0 | 0.6-1.2 | 3.2 | 8.0 | 0.7 3 |
Table source data: 1Aldwyn Clarke, ADAS; 2RB209, 2010; 3Smith, 2005
Periodic removal of the dirty surface layers is required for good management. When this material is removed and spread it should be treated in the same way as FYM.
Detailed monitoring at the trial sites has shown that there are significant surface evaporative losses and absorptive capacity of the woodchip, which will significantly reduce the volume of effluent draining from the pad.
Ammonia emissions
Trials have been carried out at North Wyke to look at the ammonia emission rates from woodchip pads compared to housing cattle traditionally. Results showed that emissions of ammonia were broadly similar to those expected from beef cattle housed on concrete yards.
The results also showed an impact of wind speed on ammonia emissions. Emissions per head of cattle were about 40% lower than current values for traditional housing. See graph below.
Relationship between wind speed and ammonia emissions, data from North Wyke Research
It may be possible to conclude that emissions from woodchip pads could be reduced by making use of fencing with windbreak material, or hedging around exposed sites.
The shelter effect may also improve welfare on exposed sites but may cause trampling hotspots.
Outwintering on woodchip pads can reduce damage to grassland
Managing soiled bedding
There seems to be no negative effect on grass growth following the application of soiled woodchip residue directly after removing it from the pad.
Dealing with dirty woodchip
The material has a high carbon to nitrogen ratio, and this was found to sometimes result in N immobilisation, especially where very fine chip or sawdust was the bedding material. Where this is the case, some composting prior to the material being spread was found to be beneficial.
Direct spreading
Trials spread soiled woodchip (1-2cm grade chips and sawdust) on grassland at different rates, with the highest rate supplying 160kg/ha N. This material had just been removed from the surface layers of an outwintering pad.
Within three weeks of application the soiled woodchip was barely evident, having been rapidly incorporated into the sward and topsoil.
Any larger chunks of material (5-10cm chunks scraped up from the base layer) were still visible in the sward. This material had not been incorporated into the sward or the soil.
Left hand picture – Application of 20t/ha soiled woodchip supplying 160kg/ha N; Right hand picture – grass sward three weeks after application.
Yields from both treatments (1-2cm and sawdust) were similar to those from fertiliser applications of 30 and 60kg/ha N. No negative effects on grass dry matter yield were seen from the application of untreated soiled material.
Experimental grass plots to assess yield response to soiled woodchip applications and fertiliser N
Composting before spreading
If waste wood has been used as a bedding material on woodchip pads in accordance with a U8 exemption then the Environment Agency has a regulatory position on their composting and use.
Composting works well for finer chip material (less than 2cm in size). Coarser material is generally unsuitable for applying to grassland as large chunks will persist in the sward even after composting. Coarse woodchip therefore requires different management – potentials incorporating it into arable soils, or ploughing in before a grass reseed.
Composting can be undertaken outside where rainfall will replenish water losses caused by evaporation from the heap. This ensures that the composting proves can be maintained for a longer period of time – from 8-24 months. One of the benefits of the composting process is the reduction in the level of weed seeds and pathogens. The composting process may however result in increased ammonia emissions and loss of nutrients, particularly N. This may mean that the product applied post composting will not have such a high N content as the material that is not composted.
The application of composted woodchip to grassland does not seem to have any advantages over spreading soiled woodchip directly from the pad.
Aeration is not necessary. Trials showed that application of composted woodchip from heaps that had been turned and actively aerated, compared with static heaps resulted in no benefit to grass DM yields.
Source: Materials and images adapted from “Improved design and management of woodchip pads for sustainable out-wintering of livestock” compiled by Project Consortium Partners including Jessica Buss (BGS), David Chadwick (North Wyke), Lynfa Davies (HCC), Ken Smith (ADAS), and Mary Vickers (EBLEX)