Chicken-wire will keep birds in, but not a cow
Just about anything else will hold in a cow, but not a horse
Barb-wire will hold in a horse, but not a pig
Hog panels will hold in pigs, but not a goat
Woven wire fence will hold in a goat.
The best fence post treatment is to soak the wooden posts in a hot bath of the following mix for a few days.
Heat gently in a 55 gallon steel drum, add ingredients in the order listed above. The mixture is very flammable and high smelling - adequate ventilation is a must!