Windbreaks Provide Shelter for Cattle
Cattle don't always need housing, but they do need shelter from the elements. Windbreaks, either natural or constructed can provide that shelter.
The downwind influence of a windbreak is 10 times the height. This means that a windbreak of 20 ft high trees will have an influence on the wind pattern 200 ft downwind (see Figure 1). If you are considering planting trees to protect a building or yard, set the windbreak a minimum of 60 to 65 ft upwind of the building or yard to be protected. The windbreak should consist of two or three rows of evergreen trees. Since they tend to grow to different heights at maturity, a variety of species is planted. For a two row windbreak, plant a row of cedars and spruce. If three rows are planted, then use cedar, pine and spruce. When the spruce are mature the bottom limbs will die down, but the cedar will continue to grow close to the ground.
When selecting a site in a bush, it is best to look for a stand of evergreens, as they will provide the best shelter, but it is important to consider both wind protection and snow patterns. You want to protect the cattle from the wind and snow, but you do not want a location where the trees cause the wind to loose all of its velocity and result in all the snow settling out and accumulating, making feeding and management difficult.
To protect barns and feedlots where natural windbreaks do not fit the farmstead plan, windbreak fences are used. A fence with a porosity of 20% (see Figure 2) provides the best wind protection. Spaced boards (Table 1) allow some air to pass through but the draft is reduced. The height of the fence depends on the size of the area protected. The usual minimum is 8 to 10 ft in height.
If snow protection is a major factor, construct a solid windbreak fence (see Figure 3). An open fence allows the snow through and it deposits on the downwind side. A solid fence, providing it is high enough, deposits the snow on the upwind side. The fence must be high enough to keep drifting snow from going over the top. Recommended height is 8ft. The area downwind from the fence will have reduced air flows, although not as great as with the 20% open fence.
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