I ran out of ferret food and was wondering if it is ok to give my ferrets IAMS cat food?

A food change done this quickly will likely not work. Ferrets need to be gradually eased into a change of food. Ferrets have been known to literally go on a hunger strike because a food that they are used to has been taken away. Even if you have a less picky ferret who decides to eat the new food anyway then you will likely be dealing with runny poops for a while.

I suggest you get on down to the pet store and just get a bag of ferret food. If you absolutely cannot get to the store put the cat food in its bowl but as I said there are no guarantees he/she will even eat it AND if they do be prepared for messy poops.

If what you are looking for is a change of food do it slowly by adding a little of the new food into the old food until all you have left is the new food. I recommend you follow these guidelines. This food chart is particularly helpful in regards to making an educated decision about what to feed your ferret. ;)
http://www.mdferretpaws.org/care/food_tr…

You will make them sick by a: changing their food quickly like that (you need to switch brands by adding alittle in over time) and b: cat food has too much fiber for ferrets and is made for a much slower digestive tract. Giving it cat food will result in weight loss and inconsistent poops.

Your cat food should say on the sack the percentages. But if you think of it cat food is made for cats not ferrets. Ferret food is formulated for the little guys to meet thier dietary needs.

For a short term solution (a day for a few) not an issue. For longer periods of time it isn't optimal nutrition for them.

Yes, but Ferret food is best.