Conservation Grazing Stocking Rates and Timing

Key Considerations for Conservation Grazing – Suggested Stocking Rates and Timing

Grazing by farmed livestock is an essential management tool for many semi natural habitats in Ireland. Some key considerations when deciding what type of animal would be best to graze a site are:

• The type of livestock and stocking density will vary depending on the objectives of the conservation project.
• The grazing behaviour should determine the species of stock chosen.
• The stocking density will be affected by the site’s ability to maintain a healthy animal without negatively affecting the quality of the habitat.
• Seasonal grazing is often necessary both to protect specific features of the habitat such as ground nesting birds and wildflowers, and to reduce the risk of damage to the soil structure and ecosystem.
• The welfare of the livestock is of the utmost importance and they should not be left unmonitored.
• It is important that a grazing management plan has clear objectives and has considered both the ecological benefits and the welfare of the livestock.
• As with all plans once the stock is actively grazing it is essential to monitor the effects of grazing on a regular basis, making the necessary changes if conditions deteriorate or the stock’s welfare is at risk. Equally the situation may occur where more animals are needed to graze an area where the grazing pressure is too low. By monitoring the site, it will also help inform others to develop sustainable grazing management plans.

Choosing the Type of Livestock

The main species of farmed herbivores in Ireland are cattle and sheep, although other species maybe considered it is often availability that determines the chosen species for conservation projects. However, cattle and sheep graze vegetation differently and this should be considered carefully especially on very sensitive sites

Cattle

Cattle are less selective feeders; they rely on a large intake of forage and if given the option do not graze vegetation below 5 to 6 cm. They can be used at sites with tall or coarse vegetation as this does not impede their grazing habits. Due to their weight, they are more likely to damage the soil structure by poaching, this may be useful if the objective is to encourage open ground for seed germination or to break up mature vegetation such as heather or gorse, but this makes them unsuitable for more fragile sites with thin or peaty soils. Their dung pats are also likely to cause local nutrient enrichment.

Sheep

Sheep are more selective grazers and can graze swards down to 2 cm. Sheep avoid tall and coarse vegetation; they are best suited to sites with short swards. They are unlikely to be an effective management tool in a habitat where the aim is to control coarse vegetation such as rushes, gorse or mature heather. On sites where the objective is to conserve or restore flowering species sheep will tend to graze out the flowering plants more than cattle as they select out plants that are most palatable. Sheep are well suited to fragile sites that are nutrient-sensitive or vulnerable to poaching and soil erosion.

Goats

Goats are selective grazers and will browse on woody shrubs and small trees and therefore can be used to control open scrub in habitats such as heather moorland, mature native broadleaved woodland and encroaching scrub in other situations.

Overall, there is often a preference for using hardy native breeds for conservation grazing as they can utilise the poor quality semi-natural vegetation better than the more productive commercial breeds, and they cause less poaching and damage due to their smaller size.

Setting a Stocking Rate

When setting a stocking rate for an area for conservation grazing it is important to consider the grazing pressure from wild herbivores such as rabbits and deer. The situation should be assessed, and an estimate included in the calculation of the overall stocking density.

Each type of farmed and wild herbivore is given an individual livestock unit which is an indication of their grazing pressure. The following table suggests livestock units for the main farmed and wild herbivores found in Ireland.

Typical Annual Stocking Rates for Different Types of Habitats

The planned stocking rate for a habitat will determine how many animals the site can support without harming its ecology. The following stocking rate tables should be treated as a guide when conservation grazing is being considered and it is recommended that regular monitoring of the site should be carried out to ensure the objectives of the management plan are being met.

Grasslands

Saltmarshes

Coastal

Woodland

Upland

Fen

Note: If the improved grassland receives fertiliser, then the stocking rate need to be increased to 1-2LU/ha

Timing of Grazing Livestock

Timing of grazing depends on several variables, these include livestock management practices (e.g. lambing and shearing for sheep), the type of livestock available for grazing, the nutritional value of the sward at the site as well as the objectives for conserving or restoring a site.

The type of stock available to graze a site may determine the timing of grazing. For example, store cattle may be able to graze for longer periods than fattening cattle, as their nutritional requirements are not as demanding. Similarly, a suckler cow with young calf at foot will require a higher nutritional diet than a spring calving cow that needs to reduce their body condition score over the winter before calving down in spring.

Many habitats in Ireland may only sustain stock for short periods of grazing and many areas are not able to sustain winter grazing without the use of supplementary feeding. Supplementary feeding is undesirable in many situations as there is an overall nutrient input to the site causing enrichment of the soil and increased risk of poaching around feeders and gateways. Grazing off swards in autumn and removing the stock over the winter period is the best approach to ensure the desired sward height is obtained for the spring.

In general, there are several situations where seasonal grazing is best suited to managing the site, these are as follows:

• Wetland sites are vulnerable to poaching, soil erosion and overgrazing during the winter periods and flooding events. Grazing outside these periods will avoid damage.
• On sites where the objective is to improve the diversity of the sward or to protect a specific flowering plant, it is advisable to close the site off to grazing livestock over the active growth and flowering period. In general, this is from early May to late July.
• Ground nesting birds are vulnerable to trampling during the nesting period. Stock should be excluded, or the stocking rate reduced.
• Upland sites may not sustain cattle or sheep over the winter period without supplementary feeding. Removing stock for the harshest weather will protect the sward and ensure the welfare of the animals. If the objective is to encourage a specific plant species, grazing before and after the active growing and flowering period will help by managing the sward composition and reducing competition.

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