Agricultural Fencing

In agriculture, fences are used to keep animals in or out of an area. They can be made from a wide variety of materials, depending on terrain, location and animals to be confined.


Wire Game Fences

The principle of wire fences is that they are supported mainly by tension, being stretched between heavy strutted posts at ends, corners, and ideally at intervals in longer stretches. Between these braced posts are additional smaller wooden or metal posts which keep the wires spaced and upright. To prevent sagging of the fence, which raises the risk of entanglement or escape, the wire is tensioned as much as the material will safely allow during construction. Wire fences are typically run on wooden posts. When less expensive or more readily available than wood, steel posts or star posts are used.


Barbed Wire Game Fences

Barbed wire is made by many manufacturers in an almost endless variety of styles and for the most part these are functionally identical. The differences reflect peculiarities of each manufacturing process rather than deliberate design of the end product. The traditional barbed wire is made from two mild steel wires twisted together. Steel barbs are attached every 10–20 cm. Barbs have either two or four points, with the two point design using somewhat heavier and longer barbs.

Barbed wire is particularly effective for containing cattle. In pastures containing both cattle and sheep, one or two strands of barbed wire is used in conjunction with woven wire to both discourage cattle from reaching over the top of a fence and to keep sheep from crawling under. Though often used in many areas for horses, barbed wire is not advised. There is very high risk of injury occurring when a thin-skinned, fast-moving animal with long legs runs into it or puts a leg through the strands.

Smooth Wire Farm Fence

Plain wire is essentially the same product as barbed wire with no barbs – either a two-wire twist or a single strand. Its primary advantage is that it is less likely to cause lacerations and cuts if an animal becomes entangled in it or rubs against it. However, animals will readily lean on mild steel smooth wire, stretching it out of shape or loosening it from the posts, and for this reason it is often used in high-tensile form, which more easily springs back to its original length. Smooth wire fencing is often used as an inexpensive material to safely contain horses and other animals that run a high risk of entanglement, usually in conjunction with a line of electric fence. Smooth wire is also used in securing fence-post braces and other uses where barbed wire is not recommended

High Tensile Wire Fence

High tensile (H-T or HT) fencing is a special hard, springy steel wire. The wire may be a single strand plain or barbed wire, or woven mesh, and is capable of much higher tension than mild steel. It permits the use of wider post spacing and is neither stretched easily by animals, nor by fallen trees or branches. It can be insulated and electrified. Because of the wide spacing of the posts, thin metal or wood spacers, droppers, may be attached to the wires between posts to maintain their spacing.

Joining HT wire is difficult because of its stiffness and its reduction in strength when bent sharply. HT wire is more expensive than mild steel, but because of the need for fewer posts, the overall cost of the fencing is usually comparable.

Because it does not stretch, animals are less likely to become entangled in HT wire. However, for the same reason, if an animal does become entangled or runs into a few strands at a high speed, it can be deadly.


Woven Wire Farm Fence

Barbed wire cannot effectively contain pigs, goats or sheep. Where these animals are to be fenced, woven wire is used instead, often with one or more strands of barbed wire at the top. For pigs, a ground-level barbed wire strand or electrified wire is used as well to prevent them digging beneath the fence.

Agricultural woven wire is identifiable by wire "knots" wrapped around each intersecting wire. Cheaper forms of welded wire mesh used in residential fences are often spot welded at junctions and as such are less sturdy and may break, creating a hazard for enclosed animals. Woven wire is more costly to purchase and time-consuming to install than is basic wire.

Woven wire with large openings has some potential hazards. Animals contained inside the fence can easily put a foot through the wide squares while grazing along the edge of the fenceline or while reaching over it, and then become tangled in the fence. It is also dangerous for wild animals that attempt to jump such fences. These can become trapped when their back feet clip the fencing and get caught. While they can be cut out, they are often seriously injured and must be euthanized. A variation, called field fence, has narrower openings at the bottom and wider openings at the top, which prevents animals from getting their feet entangled while grazing close to the fence, though is of little help if an animal becomes tangled in the openings higher up.

Horses and ponies in particular are safer kept inside woven wire fence with squares of smaller dimensions. This type of wire is also more effective for containing goats.

Chain link fencing is, arguably a form of woven wire, and is occasionally used for some livestock containment. However, due to cost, it is not particularly common for fencing large areas where less-expensive forms of woven wire are equally suitable. When used in small enclosures, it is easily deformed by livestock, resulting in high ongoing maintenance costs.

Electric Farm Fence

Electric fencing is widely used both for temporary fences and as a means to improve the security of fences made of other materials. It is most commonly made using lightweight steel wire attached to posts with insulators made of porcelain or plastic. Synthetic web or rope with thin steel wires interwoven to carry the electrical charge has become popular in recent years, particularly where additional visibility is desired.

A fence energizer places an electrical pulse from ground to the wire about once per second. The pulse is narrow and usually around 5-9 kV. Animals receive an uncomfortable but harmless shock when contacting the wire, and learn to stay away from it.