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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.

Natural Windbreaks

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.

Figure 1. Porous Windbreaks, Such As This Tree Shelterbelt Give Good Protection For A Horizontal Distance of About 10X Their Height.

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.

Windbreak Fences

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.

Figure 2. Effect of a 20% Porous Windbreak on Wind Patterns.

Figure 3. A Board Windbreak Showing the Spacing Between Planks

Shade cloth can be used as an alternative to spaced boards for the purpose of wind protection. Shade cloth can be mounted on top of a concrete wall if the wall is needed to keep cattle in the yard. Shade cloth that is at least 20% porous should be used, and it will have to be firmly supported. If the shade cloth becomes plugged with ice or snow it may be torn off in a strong wind. Another alternative to lumber is plastic mesh windscreen. This product is about 25% porous and is designed specifically for windbreaks, and is not the same plastic snow fencing.

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.

Figure 4. A Solid Windbreak Used Where Snow Is a Factor.

A windbreak in the form of a swirl chamber is used protect a building with an open front. The normal configuration is shown in Figures 4 and 5, with a windbreak fence attached to the swirl chamber to add further protection to the barn and yard. The swirl chamber is on the windward side and is set back and away from the corner of the barn. The swirl chamber should be square. The minimum recommended size is 10 ft x 10 ft, with the maximum being 30 ft x 30 ft. A swirl chamber of 16 ft x 16 ft is a good choice. The fence height forming the swirl chamber is important. It should be equal to the height of the eaves or greater. This helps to break up some of the wind patterns that come over the roof and down to the open front barn.



Figure 5. A Swirl Chamber and Windbreak Fence Protecting an Open Front Barn From Wind From the Rear.

Figure 6. A Swirl Chamber and Windbreak Fence Protecting an Open Front Barn From Wind from the Front.

Figure 7. Barnyard with Interior Windbreak Partitions Which Minimize Wind Chill and Drafts.

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