If you have a barn or shed that you keep feed in, few things are as vital as having a cat around who will earn him keep around your farm. Some of the benefits include:
Killing rodents that carry diseases and contaminate and eat feed.
Reducing the number of prey animals in the area, resulting in less wild food for predators (therefore making the hunting grounds too poor to bother hunting.)
Keeping away younger predators and scavengers that aren't confidant or strong enough to ignore the cats and set up residency in your backyard.
Removing the need to buy dangerous poisons or waste valuble time checking and resetting a dozen traps every day.
Contrary to popular belief, barn cats do - or should - live great lives. While their life span is typically shorter than an indoor cat, the quality of life is just as good, if not better. Barn cats should always have fresh food and water in front of them and still require vet check ups.
A hungry or unhealthy cat is not a good hunter - especially since cats are clever enough to pack up and leave if they aren't content with their surroundings. Barn cats hunt for the joy of hunting, and often don't even bother to eat what they have caught.
Make sure that the mouser has a space that is "his" where your other animals can't or won't go. This is especially important if you have free range chickens. Once they find out about cat food they will do less free ranging and more gorging on the new snack. Keeping the feed in the back of a comfortable den that is dark will usually keep all but the bravest chickens from traveling inside. If this doesn't work then set down one cup of feed per cat at night after the birds have all gone up for the evening. Keep increasing the amount of feed until you see a little left over in the morning. That will tell you how much your cats can clean up in a night. Still make sure that you keep the bowl of feed out of the open to discourage dogs, foxes, or raccoons from trying to steal the meal.
The type of feed is ultimately up to you. High quality feed is more expensive, but tends to keep your cat healthier longer. With that being said, there are some foods that a cat will turn his nose up at, especially if he liked what he was being fed at his old home. I swapped from a $3/lb bag of feed that had dried blueberries, rabbit, and other tasty things in it, to an off-brand cat food that I know consists of mostly corn and cardboard. But I couldn't get them to be enthused about the better feeds. They would meow hungrily and look expectantly as I poured the food, then sniffed at it in disdain, looked at me as if I had set down mud, before grudgingly eating.
Fortunately by being outdoors they can supplement their diet with grasses, insects, and rodents when they feel the need. Just make sure you never, ever feed them raw eggs. Once a cat learns how tasty a chicken egg is it's impossible to keep them away.
While some people may disagree, I feel that a barn cat should be strictly outdoors. Letting him come in at night will hinder his most productive hunting time, while bringing him in each time the weather is bad will keep him from properly adapting. After all, bringing him in to a 70 F house in the dead of summer may be nice for a few days, but will make the heat seem even worse when he is brought back outside - same with bringing him into a warm house during the winter. Cats are clever and know when and where to take shelter during a bad storm - very rarely do you ever have to worry.
Weather is one of the reasons why I prefer to have more than one cat. If something frightens them during a storm they have one another to console, and during a blistering cold night they can curl up together to stay warm.
Finding The Perfect Cat
With how over populated cats are, aquiring your new mouser is a simple enough task and you should be picky about who you bring home. After all, with any luck it will be 10+ years before you need a replacement. Because of this, the following things should be considered when adopting:
Other things to consider are gender and size. All of my mousers have been males, but that wasn't intentional. I can safely say that my toms would take offense at anyone saying females are better mousers. From what I can tell, they do a great job. As for size, larger cats have a better chance of fending off dogs or other aggressive predators like raccoons while also being able to catch larger prey such as wild rabbits. However, smaller cats seem to be faster and can squeeze into tiny spaces to ambush or catch mice. Ultimately it is up to you to decide which works best for you.
Once you have your checklist in mind for what you are looking for, check the local shelters and papers for animals that are up for adoption. There are also places online you can check, like Barncats Inc who specialize in finding great homes for fixed mousers. Don't feel forced to take the first cat that comes across your path: as mentioned, this is an animal you will potentially have for the next decade. Make sure you are completely satisfied with your choice. It's easier to pass up a dozen candidates than it is to bring home the wrong one and find someone else willing to take her.
After a long, or not so long, search, you have found your new mouser. Now that you have him, keep him confined to a pen inside the barn around the rest of your animals. While most cats won't attack chickens, some don't have a problem with attacking chicks. Also, some cats become terrified of roosters, geese, or goats. This introductory phase is both to familiarize your cat with the animals whose feed he will be defending, while also giving everyone else a chance to relax and understand that this newcomer isn't a threat.
Usually after a few days to a week, the introductions have been made and everyone has a good idea of whether they do or don't like one another. Release the cat inside the barn, petting him and giving him treats if he allows. Let him investigate his new surroundings with you there to stop any problems before they start. Keep an especially close eye on flock or herd protectors, such as a rooster or bully hen who may try to cause trouble. Expect at least one scuffle and don't bother getting involved unless it looks serious. After all - if they don't work this out in front of you they will do it behind your back.
Yes, A Vet is Needed
Rodents carry diseases and parasites that cats can get. Making sure your cat is up to date on his shots and wormer is good for him and for you. Ultimately, a barn cat is an employee who is paid in food and shelter and has health insurance that you cover. In exchange he cuts your costs by removing pests and keeps your animals healthier. While it's easy to ignore this expense, you shouldn't. A healthy cat will catch more rodents and a dewormed cat will eat less food. In the end, it's cheaper to have a vet.
Below are a list of things you need to schedule to have done by your vet. Some can be handled by you depending on your experience, but ultimately just having everything done at once is better.
Quarterly: De-worming. Over the summer you may want to increase heartworm protection to every month if mosquitoes are bad in your area. Remember that cheap wormers at pet shops don't do tapeworm - make sure the wormer you or your vet offers handles that, as well.
Annually: Once a year you should make sure that you are up to date on all vaccinations, including the herpes, calichi, and panleukopenia virus (which are typically all in one shot), FeLV/FIV (feline leukemia), and rabies (which is given once every three years).
By keeping your barn cat vaccinated, de-wormed, and well fed, you can expect years of loyal service in keeping a pest-free yard. The benefits far outweigh any drawbacks associated with having a few mousers in your yard.