Sheep shelter guidelines
Farmers, managers and those in charge of livestock have a responsibility to provide adequate shelter for their sheep. The provision of shelter allows sheep to better cope with the varying climatic extremes that can occur throughout the year and can increase their productivity.
Prevention of Cruelty to Animals Act
Sheep are kept in a variety of situations, ranging from extensive grazing to close confinement and housing. Whatever the form of husbandry, owners and managers have a moral and legal responsibility to care for the welfare of animals under their control. Basic requirements - adequate food, water, air, shelter, treatment, comfort and the freedom to move and express normal behaviour patterns - must be met.
Section 9 of the Prevention of Cruelty to Animals Act 1986 defines cruelty offences and requires that proper and sufficient shelter is provided for animals.
Provision of shelter for sheep
Healthy sheep can tolerate a wide range of temperatures if they are acclimatised and have adequate feed and water. However, shelter can improve the welfare of the animal and reduce production losses. Animals without shelter need to put more energy into normal functioning and less into production.
Animals must be provided with shelter in times of above or below average temperatures. This can minimise the impact of climatic extremes and prevent suffering or possibly death.
In free-range conditions in Victoria, cold stress particularly impacts the welfare of new born lambs and recently shorn sheep. Ewes, particularly Merinos, may not actively seek shelter, but studies have shown that the provision of shelter can substantially reduce lamb mortality. Periods of extreme heat can cause heat stress, with lambs again more susceptible than adult sheep. Heat stress can reduce productivity, cause reproductive problems such as reduced semen quality and lower birth weights, and compromise the immune system.
Adverse weather includes climatic extremes such as low temperatures with wind and rain combining to impose a severe chill factor, the sudden onset of prolonged wet and windy conditions, or heatwave conditions with sudden or prolonged severe heat. Sheep need access to shelter from these conditions. Whether natural or manmade, animals seek out appropriate shelter for the prevailing conditions.
The amount of shelter provided should be sufficient for all animals to access it at the same time, and stocking rates may need to be adjusted to allow for this. This will prevent overcrowding around areas of shade or water.
While the Merino is considered to be better adapted to hot and shadeless conditions than British breeds, all sheep experience heat stress to some degree on days of above average heat. Sheep cool themselves primarily by increasing their respiration rate, and can also lose a small amount of heat through sweating. Heat stress and exhaustion should not occur if sheep are able to find shade and rest during the hottest part of the day.
Lambs and pregnant ewes are more at risk of heat stress due to their lower heat threshold, as are sheep with a history of respiratory disease due to a decreased ability to dissipate heat through panting.
Appetite is reduced during extreme heat and can result in decreased daily weight gains and feed efficiency. Provision of good quality, highly palatable feed and plenty of shelter during periods of hot weather will reduce the heat load of the sheep and assist in maintaining normal feed intakes. Heat stressed sheep are more vulnerable to acidosis or metabolic disease, so any new feed should be gradually introduced. During extended periods of high temperatures it is necessary to provide sheep with plenty of shelter and fresh cool water. Wind flow is important for keeping animals cool and should be considered when deciding type and location of shelter. Shelter should also be provided to recently shorn sheep to prevent sunburn.
Shelter suitable during hot weather
The best type of shelter during extreme heat protects animals from the sun and allows for the cooling effect of the wind. Some options for shelter in hot weather are:
- constructed shelters using materials such as shade cloth, corrugated iron or timber
- trees with large canopies - planted individually in fields. Trees have a cooling effect due to absorption of heat by the leaves
- naturally undulating paddocks and gullies
- shelterbelts – thick hedges of trees, shelterbelts can provide good protection from sun, but should be thinned evenly to allow wind flow and planted in an east-west direction to provide shade during the hottest part of the day.
It is important that sufficient shelter is available for all animals at the same time to prevent sheep crowding and smothering. It is preferable that all animals are able to lie down as this helps them cool themselves.
Shelter and water
The importance of clean fresh water during periods of extreme heat should not be underestimated. An adult sheep requires an average of two to six litres of water a day, and up to 80 per cent more on days over 35ºC. Water sources should be familiar to animals before an extreme weather event. This is especially important when sheep are introduced into paddocks with tall pasture as they may not be able to sight the water source. Water should also be close to shelter and be of sufficient volume to cope during periods of peak demand. The number of watering points and/or water flow should be increased if a large number of animals are kept together.
Placement of troughs should be carefully considered to prevent animals crowding between fences and the trough.
Care should be taken when placing shelter near water so it does not result in animals camping around the water source, causing overcrowding and preventing animals from accessing water. It may be necessary to reduce the stocking rate into several small mobs, as even if sheep have access to several paddocks with shelter, mob instinct means that they tend to group together under one shelter or water source.
The impact of cold weather, particularly when combined with wet and windy conditions, can have severe impacts on sheep especially lambs and recently shorn animals. It is important that lambing ewes and recently shorn sheep are put into areas or paddocks that contain the best shelter or protection from the elements.
Recently shorn sheep
Shorn sheep are at greatest risk of cold stress in the first three days (or nights) after shearing, and remain at some risk for up to two weeks. Fleece growth is insignificant over this short period but considerable skin thickening occurs. The stress of shearing may also be a factor.
In areas prone to winter storms a 'cover comb' or 'snow comb' can be used if shearing in late autumn, winter or early spring, to reduce the risk should a storm hit suddenly.
Once cold, freshly shorn sheep may become extremely difficult to move so always put shorn sheep straight into a protected paddock with plenty of shelter from the cold if shearing in the colder months of the year. Cold snaps can occur with little warning so taking precautionary action with all newly shorn sheep can help prevent losses in the case of a sudden change in weather. Extra feed should be provided to sheep for up to four weeks following shearing to meet their increased energy requirements.
Check predicted weather conditions before putting shorn sheep into a paddock after shearing, so that if a cold snap is forecast, you can leave them in sheltered yards or sheds where they are better protected from the weather.
'Bad weather' in this context involves at least two of the three factors of low temperature, wind and rain, that when combined, impose a severe chill factor on a lamb recently expelled from a temperature-controlled environment. Under such circumstances, a lamb that fails to get a drink soon after birth will become progressively less able to do so.
Around 70 per cent of lamb deaths that occur between birth and weaning take place within 48 hours of birth. The majority of these are believed to succumb to the 'mismothering-exposure-starvation' complex. Losses can be particularly high during short spells of bad weather, which may coincide with peak lambing periods in individual flocks during autumn, winter or spring. Wind and rain combined has an additive effect and it has been shown that a wet coat (rain or amniotic fluid) can increase heat loss by 13 per cent, and by 18 per cent with a wet coat and wind.
Studies have shown that in cold, wet and windy weather lamb losses can be reduced by around 30 per cent if flocks are provided good shelter. Reducing the wind speed at lambing sites is a critical factor contributing to the increased survival of lambs.
Shearing within a month before lambing encourages ewes to seek shelter; however it does have its own risks, especially if a severe storm occurs shortly afterwards. Pre-lambing shearing must only be considered if ewes are in good condition and have free access to good feed and shelter. Heavily pregnant ewes should not be subject to the handling and feed deprivation that shearing involves. The use of hand shears, a cover comb or snow comb is recommended.
Sheep in full wool are liable to become cast, especially if heavily pregnant and kept in flat paddocks. At risk ewes should be kept where they can be inspected daily.
Shelter for lambing ewes
Shelter from cold wind, whether provided by topography, trees, other vegetation or artificial structures, can improve the survival of newly-born lambs in the event of cold snap conditions occurring within the first two weeks of lambing. Effective shelter protects lambs from wind, rain and, radiative and conductive heat loss, as well as enabling exposure to the sun.
Shelter should be familiar and well dispersed to encourage use by ewes isolated from the mob at lambing.
Simply ensuring that shelter is available to the lambing flock may not suffice, because well-insulated ewes may not seek shelter. This may be overcome by lambing down in a narrow paddock, well sheltered by a long shelter belt.
Shelter suitable for extreme cold include:
- constructed wind breaks such as corrugated iron along fences or hay bales placed in the paddock
- natural undulating paddocks and gullies
- sheds (open on one side) erected in paddocks can provide protection from wind)"
- forestry blocks can be used as emergency shelter for large numbers of stock, and can provide protection during sudden storms.
Tall wheatgrass stands trialled at DEDJTR Hamilton have been shown to reduce twin mortality by 50 per cent. The hedges are one metre wide and run the length of the paddock in a north-south direction, with perennial ryegrass and clover sown in between. These hedges provide good shelter for lambs as the wind speed at the lee of the hedge can be reduced to less than one per cent of that in open areas. Grass hedges are most effective when used in addition to existing shelter rather than trying to create shelter in very exposed areas.
Natural shelter such as native Poa tussocks, old logs, flax, shrubs and grasses should be retained to provide shelter for lambs regardless of their mothers' sheltering behaviour, and is very likely to increase lamb survival and possibly growth.
Shelterbelts are the best form of shelter against wind, with the 'shelter zone' spanning a distance about 14 times the height of the trees. If wind speed is reduced, cold stress is markedly reduced.
Research has shown that lamb mortality during the first 48 hours of birth can be decreased from 20 per cent to 5 per cent where a five to seven metre high shelterbelt is available.
Trees for protection from wind should be planted in a north-south direction to protect from north and south westerly winds. The trees forming a shelterbelt should be spaced evenly and be semi-permeable in order to slow the wind without creating turbulence on the lee side. Under-planting should be incorporated to prevent wind being funnelled through gaps at livestock level.
Animals that are in their last trimester of pregnancy should not be grazed where they have access to Macrocarpa stands, or Western Yellow Pine at any stage of pregnancy, as both of these species are known to induce abortion if ingested.
Stress and metabolic diseases
Sheep in poor condition (including those coming out of a drought), sick animals or those with previous history of respiratory disease, are especially vulnerable to the extremes of weather. These animals should be housed separately from the main mob to ensure preferential access to shelter and feed and expedited treatment. Moving animals already under stress requires care and planning so it needs to be done well before an extreme weather event, to prevent further aggravation of the animal's condition.
Animals that have been injured in a natural disaster such as fire or flood need protection from the elements as they will be especially sensitive to the extremes of heat, sun or cold. Stock showing signs of photosensitivity (sunburn) must have access to shade. Preventative measures are available for some types of photosensitivity, including facial eczema. Sunburnt stock will also benefit from veterinary treatment.
Feeding hay or grain to sheep prior to shearing and for three days after shearing may be of great value in reducing sheep losses, depending on the time of year when shearing occurs.
If it is anticipated that supplementary feed will be required, feed should be introduced gradually to allow them to adapt and for any shy feeders to be identified.
When sheep are in holding yards, use should be made of artificial and natural shade to protect them from extremes of wind, heat and cold. Shelter is important for young animals if they are left in yards for longer than two hours before transport and loading.
Transport of animals should be planned so that climatic extremes likely to compromise their welfare are avoided.
If transport on days of extreme heat is absolutely necessary, the journey plan should minimise the effects of heat stress on animals with rest stops planned to be in areas of shade and perhaps a water source.
Animals should only be transported during the cooler hours of the day. If it is necessary to stop, park the vehicle in the shade and at a right angle to the wind direction to improve wind flow between animals during hot weather. Duration of stops should be kept to a minimum to avoid the buildup of heat while the vehicle is stationary.
Stocking densities should be reduced to 85 per cent of capacity to ensure good air flow between animals, and drivers should have contingency plans in place for adverse weather events.
If sheep are being transported in very cold weather, vehicles may need to be halted and parked in a protected area to prevent wind chill and hypothermia in the animals. A vehicle with a solid front must be used for young stock to reduce the wind chill factor.
Feedlot staff and management must be aware of the climatic conditions and the clinical signs in sheep that are associated with temperature stress.
Sheep in feedlots need to have access to shade and shelter during high temperatures, particularly in areas where the duration of high temperature and high humidity with decreased air movement is prolonged. In these conditions sheep should be constantly monitored for signs of restlessness, decreased food intake, congregating/huddling around water troughs and the cessation of rumination which would indicate thermal load stress requiring immediate preventative action.
Where cold stress predominates, shelter (e.g. windbreaks, mounding) and allowance for additional nutrient requirements need to be provided.
The provision of shelter for sheep is an important management practice that has shown benefits such as improved growth rates and reduced mortality. Farmers, managers and those in charge of livestock have a responsibility to provide shelter so that the health and welfare of livestock is not compromised.
Remember: Provide shelter for all stock, identify areas of shelter on farm suitable for use during adverse weather events, and give special consideration to shelter for young, sick or pregnant stock.
Animal Welfare - it's your duty to care
This information should be read in conjunction with the Code of Accepted Farming Practice for the Welfare of Sheep.