I have still the same problem. They don´t exactly just walk through the fence, but mobs tend to group together at the boundary and stick their head through. They start some weird forwards and backward motion if they are "to deep" in it and from time to time one suddenly pops out. It doesn´t really matter which animal it is - although adult cows are not quite as bad as all the others. Really annoying when they trample all over the farmland or one has not many animals.
ForEverybody ToSee
I have still the same problem. They don´t exactly just walk through the fence, but mobs tend to group together at the boundary and stick their head through. They start some weird forwards and backward motion if they are "to deep" in it and from time to time one suddenly pops out. It doesn´t really matter which animal it is - although adult cows are not quite as bad as all the others. Really annoying when they trample all over the farmland or one has not many animals.
Windows Vista Home Premium SP2
Java 7 Update 51
Minecraft Version: snapshot 14w04b