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Power fencing for improved grazing efficiency

Jeremy McGill Published on 15 May 2013
Electrified high-tensile wire

We are all familiar with the old saying that “Good fences make good neighbors.”

Although this is true in most cases, other benefits must not be overlooked.

Good fences also make “good grazers.” There are many schools of thought on fencing techniques; however, they all have the same goal – to effectively control animals.

The concept of intensive grazing and superior forage management relies heavily on this crucial factor. We must be able to hold livestock on a given section of forage for a specific duration. Cost-effective power fencing can help us achieve this goal.

Power fence is a very effective psychological barrier. Confidence in properly constructed power fence systems has been demonstrated by numerous zoos and animal theme parks throughout the world.

Animals such as lions, grizzly bears and gorillas have succumbed to the effectiveness of power fence as an initial barrier that is often disguised as grass or weeds.

As cattle producers, we can share the same confidence if we use the right tools for the job. A power fence “system” consists of three parts:

1. energizer
2. ground system
3. fence components and design

If any of these three parts are ignored, the system will not be consistently effective.

Energizers
Energizers are commonly rated by stored joules (unit of energy measurement). Joules are very similar in concept to horsepower.

Tractors with more horsepower can handle greater loads. Length of fence, vegetation and type of fence wire must be considered when selecting the proper energizer.

Low-impedance energizers are able to shock through vegetation more effectively than energizers using older technology. Using energizers of this type eliminates the risk of fire and will not result in poly wire melting when in contact with grass.

Generally speaking, low-impedance energizers are simple, safe and effective. Mains powered/110-volt energizers are more cost-efficient per joule than battery or solar options and only require a couple of dollars per month worth of electricity to operate.

Always use a mains energizer if possible. Consult with your fencing supplier to determine the appropriate size unit for your needs.

Ground system
Grounding is perhaps the most neglected component of many fence systems. According to most university extension experts and USDA/NRCS engineers, three ground rods, six feet deep and spaced 10 feet apart are the minimum recommendation.

Never attach copper to steel. Electrolysis can occur and result in corrosion, which weakens shocking power. Use galvanized ground wire and galvanized grounding rods to avoid this problem.

Consider that most energizers use galvanized or stainless steel terminals – not copper. Think of your ground system as an antenna that gathers electricity in order to deliver the shock to the animal.

Modern satellite receivers can tune in to more television channels than the “rabbit ear” antennas of the past.

A hose clamp holding a piece of copper wire to a rusty T-post has been the weakest link of many electric fence systems.

Fence components and design
There are several key points to consider when designing a power fence system. Larger wire diameter increases the amount of electricity that can be conducted.

Seventeen-gauge steel wire is not as effective as 12.5-gauge high-tensile wire, for example. Furthermore, class III galvanization of steel components will significantly reduce the chance of rust.

Rusty wire is a poor conductor. Using high-quality, UV-stabilized plastics will reduce the amount of maintenance required as well.

Purchasing the cheapest insulators, temporary posts or poly wire is tempting at the checkout counter but can result in a bad experience in the field after they have failed as a result of quality.

When properly designed, electrified high-tensile wire can prove to be an extremely effective perimeter fence.

However, a completely electrified perimeter is not mandatory for intensive grazing. In many cases, we can utilize an existing physical barrier type fence such as woven/barbed wire or wooden plank to meet our needs by adding a single strand of electrified high-tensile on offset insulators. Advantages of an offset wire are:

1. It adds a psychological barrier to keep stock from pressuring the fence (we have all witnessed a new woven-wire fence that has patches of hair at every hinge joint after the first few weeks due to cattle rubbing).

2. It creates an “extension cord” for electricity to be distributed around a large pasture which allows for temporary cross-fencing – ultimately yielding improved forage production through intensive grazing.

3. It allows opportunity for a “training fence” to acclimate cattle to power fence when attached to a woven-wire holding paddock.

Many types of offset insulators are available. Options range from insulators that attach via wooden/steel posts to devices that attach to the woven/barbed wire between posts.

Ideal offset distance is five to 12 inches from the non-electrified fence. Note that a 12-inch offset reduces the risk of a short occurring and allows for greater distance between insulators.

Once a power distribution has been established around a pasture, the gateway to intensive grazing can be opened.

Intensive grazing can be thought of in several forms, ranging from simple rotation (week), “mob” (day) or strip grazing (stockpiled dormant forages). Any of these practices can be carried out efficiently by utilizing temporary fencing.

The most common type of portable temporary fence is poly wire. According to animal scientists, white wire provides the best contrast against backgrounds of lush green forage during the growing season and discolored stockpiled forage during the dormant season.

When selecting a poly wire, consider the number and composition of metal strands that are woven into the plastic material.

Poly wire containing a greater number of metal strands will have the ability to effectively carry electricity over longer distances.

This is due to resistance. A six-strand, stainless-steel poly wire is typically only effective for a quarter-mile due to resistance.

Reels are an essential tool for handling poly wire. Using one allows for versatility of payout, convenient handling and can also considerably extend the life of the wire.

Most reels are equipped with a metal band/hook that is insulated from the wire itself – allowing attachment to a non-conductive fence while power is supplied to the poly wire from the opposite end via gate handle.

Once wire has been stretched across a pasture, step-in posts can be added every 40 to 60 feet to complete the fence.

Styles of temporary fence posts can range from pigtail-type posts that are designed to accommodate a single strand to poly posts that can hold multiple strands.

Tumble wheel devices
Alternatives to traditional step-in posts include tumble wheel-type devices. Single spans of poly wire can be easily moved in a matter of minutes by simply holding tension on one end of the strand and walking to the next section of forage.

The wheels roll with the fence – eliminating the need for step-in posts. Cattle that are trained to power fences can be successfully contained by a single-strand cross-fence. It is important to note that poly wire is never recommended for boundary fences.

Summary
Power fencing can add to the efficiency of any livestock operation. Practically any animal with legs can be controlled by a properly built system.

Temporary electric fencing has proven itself by saving time and money when used as an instrument for intensive or stockpile grazing. Every day spent grazing is a day without hay.  FG

PHOTOS
TOP: When properly designed, electrified high-tensile wire can prove to be an extremely effective perimeter fence.

BOTTOM: Using tumble wheel devices, wire can be easily moved in a matter of minutes by holding tension on one end. Photos courtesy of Jeremy McGill.

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