There is no such thing as an inhumane way to kill a rat, 'orrible nasty creatures that cost the country a small fortune and as has already been said spread all kinds of diseases not only to stock but humans as well.And eat my electric cables and water pipe
. Unlike mice rats have to have a source of water in the form of a dripping tap or similar. Rats need 3 things to survive, food, warmth and moisture eliminate one of these and you won't have a rat problem. Bicarb\baking powder is another good killer in a bait. Rats can't pass gas, bicarb produces copious amounts of it, I'm sure you can work the rest out! They hate the smell of diesel as well, been used effectively down rat holes, not very environmentally friendly but needs must sometimes.
Every dead rat is a rat less. Bain of my life