I have a cat and 4 kittens (5.5 months old), all healthy and recently spayed. They're on a mix of dry (Acana), canned (various, will run out for good soon), and homemade raw. The cat was on dry/homemade raw at her breeder's, but when I took her, I decided that it was too much pain in the neck and switched her to dry/canned. When she was nursing, I started feeding her and the kittens raw, which all of them ate well enough, and was planning to wean them off canned (which is not available here anymore anyway). At some point (a little over a month I think) the cat and one of the kittens stopped eating raw, in the middle of a batch (so it couldn't have been because of changed ingredients), with no other reasons I noticed or could think of. I gave them a week to be fussy, then started leaving them less dry so that they're hungry at dinnertime (I play with them anyway), and started experimenting with additives (the only thing that worked was sprinkling their food with dried breadcrumbs, and even that worked exactly twice). Then I left them alone for a few days before getting spayed, because they were getting noticeably thinner. After spaying they were on prescription food for a little under a week, then we were at it again. After stoically half-starving for a week, the cat ate raw 2 or 3 times (the kitten still didn't), I started giving them their regular amount of dry, and the cat stopped eating raw again.
Frankly, I'm out of ideas. I tried every safe additive I could think of that is locally available, I let them sniff every ingredient of their food by itself to check if there was anything they didn't like, I tried different methods of defrosting and different temperatures and conditions (completely raw, slightly cooked...) of the food. What else can I do?