What has happened to respect?

It is essential that you assert your authority on this situation because if the children come to any harm, regardless of how many times you have previously warned them, you could be responsible for the cost of their health care just in the same way as you would be if you were the cause of a traffic collision or were negligent in any way which could potentially lead to the harm of others. It may be worth explaining to the father the dangerous situation into which his children are putting themselves and that you simply have the welfare of his children in your best interests. Would it be possible for you to arrange a time when the boys could spend time with your horses under your supervision or alternatively for you to install measures which would prevent the boys from gaining access to your pastures when you are not there? It is highly irresponsible of their parents to demonstrate such a blatant disregard for the care of their children and in too many cases like this, people get hurt. You are exercising your responsibility of your livestock by presenting these cautions to your neighbours and again to their children so they are fully aware of the risks and they ought to exercise their responsibility of controlling their children! It clearly not only demonstrates a lack of respect for your wishes but also a lack of common sense and correct moral discipline. Although speaking in a strictly legal sense, what they are doing is essentially trespassing and would never have been forgiven if I had been guilty of the same thing as a child.

I was just talking about this today with my pastor. Respect is gone from our youth and it is a real shame. They no longer respect their parents, teachers, elders, etc. It makes me sad to see how some of them act. I am actually embarrassed by some of their actions too.

You don't mention how old these boys are but your concerns are valid. If something were to happen to either one of them while on your property then you would be responsible. You need to be firmer with the parents of these boys. The parents should know where their kids are. They have no business being on your property when you are not home.