Some states have realized these types of fence laws are no longer realistic and have ruled them to be unconstitutional on fifth ammendment grounds of taking property without just compensation.  That is exactly what the current Iowa fence law does to those who do not own livestock.  The law does not work for the guy who has no livestock.  I am normally pro livestock on most issues and have a fair amount of it myself, but this fence law needs to be repealed.  That being said, it's not the most serious issue facing our country, state, and way of life.  It's just one of those things that annoys folks from time to time (self included).