Liquid baits, however, are much more likely to be consumed by non target animals, so great care must be taken when using liquid baits. Food baits won't work if the rats can get a regular food supply. Oh, you may get a few, but you won't get all of them. This is where experience comes in. You will have to be able to recognize every food supply within 100 feet or so.
Rats are omnivores and can eat almost anything.
They will even flourish on animal droppings and nothing else. So if you can't control their food or water supply, you will have to use a tracking powder, usually only available to exterminators. The tracking powder is placed in their burrows or runs and is transferred to their fur and feet, then ingested in the normal course of their cleaning routines. Successful rodent control requires close monitoring for maximum effectiveness, and experience in assessing the results. Well, you can use just about any rodent bait you can buy at the hardware store.