That is a little simplistic view. Lets assume for one second you did tarmac it in and the animals caused damage.
Cattle are not under control such as a dog. They are free roaming, like the law says cats are. Owners of cats are not liable for their actions.
Its the same here - you moved to a farm, knowing there were cattle.
The cattle roam - you know that. Therefore the farmer cant be negligent.
Even if I am wrong about that and the Farmer is negligent, any Judge would ask whether or not you knew filling in the grid with tarmac would allow them to roam about.
The answer has to be yes - therefore any damages you may have been awarded would be reduced to zero, because you would have contributed to the cattle escaping
Its like moving to Heathrow and complaining about the aircraft noise. Therefore if you moved to the farm, it would have been reasonable for you to expect cattle.
That being the case it would have been reasonably obvious if you filled in the grid (the thing protecting your land) then they can roam around.
I am sorry if this is not the answer you want and certainly not the one I want to give you, but I have a duty to be honest.
Can I clarify anything for you about this today please?