For the perimeter of the pasture, use permanent, multi-strand, high-tensile electric systems. The number of wires will vary according to the livestock you wish to contain. Horses and mature cattle can quite often get by with three wires, while small calves, sheep and goats may take five or six.
The best posts to use in areas with snow loads and wildlife has been proven to be solid fiberglass. There are no plastic insulators to break, and the flexibility of the post helps to overcome side loads.
There are two common mistakes that people tend to make when trying high-tensile fencing for the first time:
Posts too close!
Wires too tight!
Post spacings of around 50 feet are adequate because of the nature of high-tensile wire. The wires should be tightened just to the point of removing most of the sag between posts (around 150 to 200 lbs. per wire). This accomplishes two things. First, this design is flexible, allowing the fence to absorb wildlife pressure and snow loads without breaking. Second, less materials are needed so the initial purchase cost and the labor required to install the electric fence is less than conventional fencing.