Er, it's really not that easy to prevent. I have all my pellet feed in metal bins, but the rats still find food because there's wild areas out there, neighbors I can't control, etc. And then when they can't find food they dig deep in search of it, oftentimes attacking larger livestock (like my rabbits) or moving into houses. That's what happened here. Some people have had them attack adult chickens before on the roost, biting their feet and even killing them. Forget about having chicks or baby animals with rats around. You might as well kill them yourself the day they're born. And the rats being hungry doesn't fix that problem.
Not to mention if you have animals that require hay or straw you're boned. That's literally a food and nesting breeding ground for rats. And don;t even get me started on gardens and trying to grow your own food with rats around. Or how they eat eggs....
So, no it's not. As for snakes a majority of them don't touch the dead rats either because they're, well, dead and cold instead of alive and warm which is what most snakes look for. I've kept enough of them to know. And even studies show snakes are on the bottom of the list for percentages of animal deaths due to rodenticides.
https://www.pctonline.com/article/secondary-poisoning-concerns-with-rodent-baits/
Actually it is that easy to prevent. There are wild sources of food but it takes constant work for the rat to survive and even then it cannot overpopulate the local food sources before famine sets in for all the wild mice and rats. Plus the risks of foraging in the wild from predators. Within days of eliminating the feed source, the chicken feed, most rats will have no choice but to move on. Nesting sites are a dime a dozen if you are a tunneling rodent, consistent food sources are another matter.
Rat infestations are caused by humans leaving waste or food in large quantities. Put the feed in a metal bin. Buy a proper treadle feeder. Problem solved in nearly all situations. Colonies of rats do not survive in the wild nor will they survive unless careless humans leave feed available for them to build up numbers.