What is the cheapest, yet most reliable, cattle fencing avaliable?

The type of fence you need for cows is actually not as simple as it seems.

The type of fence needed depends on the "traffic" volume that such areas will experience. A fence that can withstand a lot of pressure and is situated in a high-traffic or high-volume area (such as those in and around handling facilities) needs to be robust, strong, high, and sturdy. A barbed-wire fence is a poor choice for such areas, as are temporary electric fences. Iron stand-alone panels, wood fences with thick boards (usually 2" x 6" boards work) and large posts sunk around 4' into the ground, or a fence made from railroad ties, steel crash barriers or even piping used for oil pipelines will also work, especially if you want to make use of materials that are considered throw-away from other industries, save your money, and have an will to work with materials instead of buying from Fencing/handling facility suppliers--and have a knack for learning welding and cutting metal.

Fences that aren't going to see a lot of pressure--like pasture fences, corral/sacrifice area fences, can also be steel panel (especially those corrals which see higher volume of cattle for a longer period of time than what is normally used for the pasture), barbed wire, high-tensile wire, or temporary electric. These fences still need to be strong or create the impression to cattle that they are strong and not to be tested (as with temporary electric and hi-tensile fencing), but they don't have to be as high as what you would build for working cattle in a handling facility. Barbed-wire and high-tensile wire fences need only to be around one metre or 4 feet high at the minimum (some can go about five feet in height, though that may be slightly higher than recommended), with at least four wires from top to bottom, spaced around 12 to 16 inches apart. Eight-foot-tall posts are sunk in three feet deep, with three posts at each corner set closer together to allow for cross-bracing, as well as in the middle. Cross bracing uses the laws of physics so that the fence doesn't collapse in itself when the wires are tightened, and makes the fence much stronger. High tensile fencing uses the same physical properties as a barbed-wire fence, except that the wires that make up the fence are smooth (not with sharp barbs), and electrified.

Temporary electric fences are shorter, lighter and physically significantly less stronger than any type of fences mentioned above. The posts are small, light, usually fibre glass, and are either made for a single wire (such as pig-tail posts), or for more wires like poly posts are. The top wire, especially for cattle or horses, is set at a height of about 36 inches, or nose-height (so that when the animal touches the wire with its nose it gets a shock), and the second wire, should it be placed, is set around 16 inches below. Temporary electric fences are powered by solar-powered or battery-powered fence chargers that also come with an 8' tall (some much taller) ground rod to keep the fence grounded.

As with all fences (including board fences that are lighter than ones that may be built for a handling facility), posts are set along the fence line at lengths varying from five feet apart to 20, depending on the type of fence, the amount of pressure it is likely to receive, the topography, and how many wires make up that fence. Usually, posts need to be closer together if they're in high-volume areas.