The best thing I have found is to use Basic H. It was originally made over 50 years ago as a cleaning agent and is still around today. Although it wasn't made to kill ants, I have found that it kills them instantly! I've been told that it does that by penetrating their exoskeletons and drowning them.
No running to another nest, or worries that it won't kill the Queen! In fact, I have timed it... only about 5 seconds after it hits them and their dead!
It is 100% nontoxic so it won't hurt to be sprayed around the nests, near your cattle or even near water. You just mix 1/4 teaspoon of it in 16 oz of water so it is very cheap. A 16 oz bottle of Basic H makes about 5,000 bottles of it so you will always have it handy! I always keep a bottle ready. Its literally the best thing I have ever found and will never use anything else!
Here's the website where you can order and learn more about it: www.help-me-get-rid-of-ants.com.
Basic H product guide
[ATTACH=CONFIG]246472[/ATTACH]