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Traditionally, usage of land has been demarcated by fences - often in combination with geographical features such as rivers and impassable rocky outcrops, or other prominent land marks such as drystone walls and tree lines. Fences are also associated with land use and livestock management - either precluding access by livestock to cultivated crops or improving utilization of veld and pastures.

Until relatively recently all farm fences were of barbed wire, supported by iron standards and droppers, between substantial straining posts. Fences of this kind are both a physical and psychological barrier to livestock and intruders. A major drawback of "conventional" fencing of this type is the expense involved: the cost in April 2000 for a 'standard' 5 strand barbed wire fence was R4 033 per kilometre.

Recent advances in (electronic) technology have ensured that electric fences now offer a viable option to barbed wire fences in most situations - with the added advantages of adaptability and significantly improved cost effectiveness.

Principle of electric fencing

Electric fencing is based on a simple principle: Energisers have two terminals, demarcated "Fence" and "Earth/Ground." A thin, insulated wire is charged with electric energy from the "Fence" terminal. A second, thin wire is connected to an earth. Whoever/whatever closes the circuit between the two terminals receives a substantial, safe (low amperage/high voltage) electric shock.

Equipment and construction

The "heart" of the electric fence is the energiser. Most modern energisers generate approximately 5 000 volts. The ability to sustain this charge depends on the capacity (measured in joules) of the energiser. Small energisers (1.0 joule) are adequate for powering small networks (15 km) of fencing and strip grazing applications. Large energisers (20 joules) will power networks of up to 175 km under normal conditions. The most effective energisers require either a 12 or 24 volt wet-cell (tractor type) battery, or A/C mains as power source. Specialised power sources such as solar or dry-cell (torch) battery models are less common.

Careful selection of an appropriate energiser is essential. Consideration should be given to the purpose of the network (security and/or grazing management), the size of the network, the type of threat/animal to be controlled, the ease of maintenance of the energiser, and the proven service record and reliability of the supplier.

Insulator quality is of paramount importance in electric fencing. The purpose of insulators is to ensure that the full amount of energy discharged into the wire is channelled through the intruder/animal when the circuit is closed. Insulators manufactured from fibreglass-type compounds, treated with fire-retardants and ultraviolet radiation stabilizers during the manufacturing process are the most reliable and cost effective (some are still performing perfectly after 20 years of continuous use). High density polyethylene insulators tend to fail when subjected to fire, and become brittle after a number of years' exposure to sunlight. Porcelain insulators are highly susceptible to physical vandalism. Used and discarded plastic water piping and/or rubber inner tubes are not at all suited as insulators.

The "earth" section of the circuit is as important as the "live" or "insulated" section.  Furthermore, the larger the output capacity of the energiser, the larger the surface area of the earth-pegs required. Ideally, earth-pegs should be sited in areas which remain permanently moist (for example in close proximity to a gutter down-pipe, down-slope from a drain, near a small stream or natural spring). A single earth-peg made of 20 mm galvanised water-pipe driven vertically into moist soil to a depth of one metre is adequate for a small energiser (1.0 joule output capacity). At least 20 such earth pegs used in a similar manner are necessary for a large (20 joule output) energiser. Clearly, all earth pegs must be interconnected with each other and the earth terminal of the energiser. Stainless steel or copper piping ensures even better earthing. With regard to the actual fencing used, fully galvanised baling wire (2.5 mm diameter) is the most practical for temporary (6 months or less) and semi-permanent (less than 2 years) use. High-strain, steel wire (2.0 x 2.6 mm) is recommended for permanent use (2 to 10 years). Purpose-made nylon wire, braided with 6 strands of stainless steel wire, is recommended for strip-grazing purposes, or those occasions where a network will be used for 3 - 4 weeks at a time and then removed. It should be noted that different soil types have different (electric) conductivities. This has a direct bearing on the fencing configuration used in any situation.

On heavy, damp, clays (and areas under irrigation) all wires in the fence should be "live". In dry areas, on sandy soils, or in areas where the soil surface is covered by dry, non-conductive material, wires should be alternatively "live" and "earth".

When constructing the fence the following basic principles should be adhered to:

1. Fence strands should at all times be parallel to the soil surface and to each other.

2. The distance between strands should be such that the animal/intruder chooses to retire from, rather than proceed through, the fence once shocked.

3. Fence voltage should be maintained above 3 000 volts for wooled sheep, 2 000 volts for cattle and goats and 1 500 volts for thin skinned animals such as horses and pigs. 

The fence standards on relatively flat topography can be as far apart as 50 metres with droppers in-between at 15 metre intervals.  For control of domestic livestock (cattle, calves, sheep, goats (and even dogs!)) it is seldom necessary to have a fence taller than 900 mm above the ground. Security and game fences should be 2 000 mm tall.  Ideal strand spacings within the fence are shown in the Table.

Problems and fault-finding

Problems with electric fencing do occur. However, if good fencing principles and techniques are followed when the fence is constructed, these problems can be minimized. The most common faults include:

1. Voltage "leakages" arising from:

1. Dead shorts - as a result of a direct connection to ground/earth 

2. Vegetation - high volume of actively growing, lush vegetation contacting live wires

3. Cracked or weathered insulators giving rise to cumulative leakage

2. Poor earth system:

1. Inadequate surface area of earth peg(s) 

2. Drying of soil around the earth peg(s)

3. Loose or corroded connections to the earth section of the network.

3. Loose or corroded connections in the "fence" section of the network. The use of "reef" knots or "figure eight" knots (in preference to double loops) and use of galvanised line clamps reduce the incidence of these possibilities.

4. Faulty energisers - a problem which may occur after electric storms and lightening strikes on the fence.

A number of desirable and useful accessories are available for use in electric fencing. However, four items are deemed to be essential. These are a digital volt meter (for accurate measurement of fence performance), cut out switches, a lightening diverter and an alarm linked to a warning mechanism (siren, buzzer or flashing light). The alarm should be placed on the end of the fence furthest away from the energiser and is used to warn the operator when the output of the fence between the energiser and end of the fence drops below a predetermined level. In the event of a voltage drop (reasons may include a cut fence; fence 'shorted out' by an animal/tree branch/intruder; vegetative material causing leakage) voltage readings can be taken and the cause identified. Cut out switches significantly reduce the amount of "down-time" lost in tracing and rectifying faults. These switches are placed at strategic points in the network and are used to isolate individual sections when fault-finding.

Conclusion

Electric fencing presents a viable option to conventional barbed wire or prefabricated fencing. Provided it is properly constructed and well maintained, it is more adaptable, convenient and cost effective than conventional fencing.

Strand spacings for electric fences

* Note that for use in security applications all strands of similar charge (polarity) are connected in "series" and not: parallel" as is the case with grazing control fences

 Developing an effective rotational grazing strategy doesn’t require a computer, CAD drawings or even graph paper and a calculator. As Vince Hundt quickly discovered, all it takes is a cattle producer with a keen eye and the proper equipment.

"If you want to be successful in grass-fed or grass-finished beef in today's business climate, you have to be very focused on the quality and care of your pastures," says Hundt, owner/operator of St. Brigid's Meadows, a certified organic farm specializing in 100% grass-fed beef in southwestern Wisconsin.

Hundt runs approximately 175 head of primarily Angus cattle on two large pastures – split into 40 acres and 56 acres of 75 head and 100 head respectively.  He explains he started utilizing rotational grazing about ten years ago.

"I was slow to become aware of what is one of the most significant paradigm shifts in my lifetime," Hundt admits. "Rotational grazing is a seminal movement and is the brightest light in agriculture right now."

"With rotational grazing, the farmer walks out to his animals, and with his own feet and his own hands, sets the fence – no chemicals, no tractors, no combines," Hundt explains. "It is better for the animals, for the land, for the environment, and for sure – definitely the consumers. It's a game changer."

Hundt says rotational grazing works because of the right tools. He is committed to utilizing Gallagher products for all of his temporary fencing needs.

"Gallagher offers everything for a producer to get the job done right the first time and also be able to use the equipment for years to come," says Dane Headley, Territory Manager for Gallagher.

To have a successful rotational grazing strategy in warm conditions, Hundt says you must utilize three tools: portable fencing that is easy to use, portable watering that is easy to use, and a portable shade. "If not, the animals are stranded in the sun. And that's torture – there's no place to hide from the sun," he says.

"It is important to keep the cattle cool," he explains. "About 45 degrees is the perfect temperature for most cattle. When it's very warm, there is nothing more certain to reduce feed intake, weight gain and milk production than high heat."

Hundt says it's the radiant temperature of the sun that is of concern.

"The energy from the sun is absorbed by the cattle, their core temperature gets raised and they stop eating. All they need is some place to get out of the sun," he says.

To combat the summer heat, Hundt utilizes the product Shade Haven– large portable shade structures designed to keep cattle cool in pastures.

"Shade Haven works great for keeping my animals comfortable when temperatures rise while at the same time giving me an effective grazing tool to improve my pastures through the precise placement of nutrients," says Hundt.  "Wherever I put the Shade Haven, that is where the animals will be and that is where the nutrients are deposited."

Hundt reminds fellow producers that developing an effective rotational grazing strategy in varied climate environments doesn't need to stress the cattleorthe farmer.

"Begin with an individualized plan for your operation. The right tools and the cattle will take care of the rest," he says. "All it takes is to move the fence, move the water and move the shade, to change the world."

Calving season brings in newborns which can make for a loud, raucous fall when it’s time to wean.  It’s surprisingly quiet, though, with a practice called fence line weaning.  Call it a gentler, kinder way to separate a calf from its mother, it allows the pair to remain close and greatly reduces stress on both. 

Mark Goes, an expert on the process, spends part of his time as an instructor at Southeast Community College in Beatrice, Nebraska and the rest of his time as a small cattle rancher.  He got into the process, which he calls ‘pasture weaning’ while working with his students in 1998 in a Ranching for Profit class.

“We wean as early as possible,” said Goes.  “"A calf's rumen is inoculated to digest solid feeds by 4 months of age.  This also coincides with the time that dam's milk production begins to decline.  We like to get the younger calves weaned and on a solid feed diet as soon as possible, thereby meeting the performance demands of the calf more effectively and freeing up more pasture to run more cows."

Goes deals with just 30 animals at home and a maximum of 60 at the school.  “The University of Nebraska is doing fence line weaning with herd sizes of 250 or more,” he said.

Goes experience at home as well as the college shows the wean stress is over in 2 to 3 days.  “Calves get over it faster than cows, all they need to learn is where to eat” he said.  “We use a nanny to show them the ropes – where the feed and water is.”  

“A cow’s milk production continues and she wants some relief so what we’re really doing is weaning the mother.”

A power fence is critical to the process.  Goes uses a simple and inexpensive two wire fence and an energizer from Gallagher to control his animals.  Explaining its effectiveness, Gallagher president Erwin Quinn said “An electric fence is a psychological barrier that doesn’t require great strength to be effective. It must be well designed and constructed to absorb some pressure from animals, snow and wind and the energizer must have enough power for the length of the fence and for the animals being controlled.”

A pulsed electric current is sent along the fence wire, about one pulse per second, from a grounded energizer.  When an animal brushes against the fence, a circuit between the fence and the ground is completed and the animal feels a short, sharp but safe shock.

Most people agree that posts and woven wire won’t do.  “Weaning calves are like sheep,” said one proponent.  “They’ll bunch up next to the fence and, sooner or later, they’ll push through.  The power fence prevents them from doing that.”

To prevent fence line crowding, Goes said it’s important to eliminate corners and place food and water sources away from the fence. 

Backing up Goes’ real life experience are many scientific studies.  California researchers, for instance, tested the effectiveness of fence line weaning a few years ago.  They weaned a group of calves with only a power fence between them and their mothers and compared them to calves weaned totally separated from their mothers.

They found that fence line calves and cows spent about half their time within a few feet of the fence during the first two days.  Fence line calves bawled and walked less, and ate and rested more than the separated calves.

All the calves were placed together 7 days after weaning.  Even so, at two weeks, the fence line calves had gained 23 pounds more than separated calves.  At 10 weeks, fence line calves gained an average of 110 pounds compared to 84 pounds for separated calves, indicating the stress from weaning was an ongoing problem. 

Goes agrees with the research.  He noted that at harvest the fence line calves still showed more weight gain and better quality meat than traditionally weaned animals.

1. How does an electric fence work?
2. How does a ground work?
3. How important is the grounding system?
4. How many grounding rods do I need to make my fence work? How do I install them?
5. How do I select the correct sized energizer?
6. What are volts, amps and joules?
7. What does low impedance mean?

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Gallagher’s range of gate hardware leads the farm gate market, and for good reason. From day one, the goal has been to continuously meet customers’ needs through a focus on quality, innovation and design.

• Innovation and Design
  An in-depth understanding of farmers' and contractors' requirements has been paramount in the production of high quality, practical product design. The combined commitment of a full in-house design team, research and development group, and Gallagher territory manager force ensures Gallagher products are on the edge of design.
   
• Quality
  Gallagher has a well-deserved reputation for quality products. The use of robotic welding, semi-automated gate bending, hot dip galvanising and no waste thread rolling ensures all Gallagher gate hardware have greater uniformity, superior strength and durability. Gallagher's products are produced completely on site, which also ensures the highest standard of quality is maintained throughout the entire manufacturing process.

So when it comes to farm gate systems, insist on Gallagher for:

• The complete range - designed in association with farmers to meet their special requirements
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