Producers use a rotational grazing system to keep pastures in better condition, and electric fencing is often used to effectively keep animals in specific areas.
Fred Martz, animal science research professor at the University of Missouri, said electric fencing is always a good option for producers because of the flexibility and low cost.
“Economics and suitable control of the animals are two benefits of using electric fencing in a rotational grazing system,” he said.  “Electric fencing can be built for 10 to 30 percent of the cost of woven wire fence.”
Martz said the perimeter fence should always be a permanent fence. Divider fences can be semi-permanent or poly tape, and either type of divider fence can be pretty movable.
“I have seen producers put fences in the wrong place and later find out that they should have been located a little differently, but that is why it is good to build them so they can be flexible and moved if necessary,” he said.

Martz recommended using a 12.5-gage smooth wire, polytape or polywire with at least seven small strands in it. Polytape and polywire are lightweight, easy to move and can be hand stretched. Polywire looks like colorful polyethylene binder twine laced with several strands of wire to carry the electrical current.

Chargers and Grounding
Martz said to look for a reputable company and economical price when choosing a charger (also known as energizers or controllers). Producers should size the charger to the length of fence. Most fencing should have at least a six-joule charger, but if the fence is a big system, the size may run up to 15 or 20 joules. Fence chargers are typically powered by batteries, solar power or by mains (120 or 240 volt AC power) and can last between 10 and 15 years.
Martz said producers should not be afraid to buy a more powerful energy source than what is needed at the time.
“Over the years weeds, grass and brush will grow and put a ground load on the fence,” he said.  “The larger chargers give better performance under these conditions.”
Improper grounding is the cause of most problems associated with electric fences. The current generated by the charger is sent out to the fence and passed through an animal into the ground.  Ground rods, which are connected to the charger and buried in the ground, are used to complete the circuit.  
A rule of thumb is to have three feet of ground rod per joule of energizer output. Ground rods may be 1⁄2 inch or larger diameter rods or 3⁄4 inch or larger galvanized pipe and are usually six or eight feet long. Grounding produces a suitable electric shock in all kinds of environment – dry and wet.

Posts and Tighteners
Martz suggests using non-conductive fiberglass posts or the new PowerFlex posts if at all possible. He said to avoid using iron posts because the increased possibility of shorting. However, if steel or iron posts must be used, plastic or porcelain insulators should be attached to the posts and the fencing material should be attached to the insulators.
Martz said tighteners keep the fence tight so that when an animal pushes up to it the wire will make good contact and give a good shock. Tighteners should be located about every one-quarter mile to adjust tension.
Overall, Martz said electric fences are the key to low-cost and effective fencing for managed grazing.  He said using quality materials, keeping the wires tight and clearing trash, tree limbs and other debris off the fence will help producers get the most of their time and money.


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