No experience with hitting a cow.  But In Iowa the railroad is responsible for a legal fence, I actually got them to pay me for installing a fence along the RR.  Took a lot of calls and emails but it happened.

Crazy thing is they tried to low ball me to have me install the fence, I said no I wasn't equipped to fence through swampy tree filled areas.  They hired a 3rd party in the meantime to complete the fence but didn't tell me that.. It got dry in the fall and I could actually get to the the area so I built the fence figuring they would never show up.  They contracted the 1/2 mile of high tensile out for 30k dollars!!  I actually billed the 3rd party contractor, they happily paid me 6k and kept the other 24k and did nothing.