I just have to say how it great it is that you have a kitten willing to eat whole prey! Kittens seem to be easiest to switch over to a healthy raw whole prey/prey model diet, so you have a really great opportunity to get him used to eating raw meat and bones before he gets older and learns to be lazy/picky.
About the whole prey (rats, mice, etc.) you can pretty much offer your cat whole prey as often as you want (and he's so lucky to have the chance to get FRESH rats! Tell Voldie what a lucky kitten he is!). If he eats the whole thing he's getting a perfectly balanced meal - cats evolved specifically to eat rats and mice, so they pretty much contain most of the nutrients a cat needs! I say 'most' because given the chance cats would also eat insects, small reptiles or amphibians, and birds. The best way to make sure your cat gets all the nutrients he needs is to offer him a variety of prey items - unfortunately not everyone can get a steady, cost effective supply of a variety of whole prey animals.
That's why prey model is a good way to keep costs down/make sure your cat is getting a variety of different kinds of prey. Prey model is essentially a deconstructed mouse that you're recreating with meat/organ/bone that you can buy right from local supermarkets and butchers. This is EXTREMELY convenient and cost effective - at least I've found it to be! With whole prey and a properly balanced prey model diet you wouldn't need to supplement your cat's diet with any canned food or any other supplements (unless you decided to keep canned food on hand for convenience sake!)
Depending on how much you and your cat like the ground food it might be a great option, but I've had a lot of problems with my research into local ground raw mixes. You want to make sure that your cat is getting a certain ratio of muscle meat/edible bone/organ meat to keep from over or under dosing on any one nutrient. Organ meat is very inexpensive, so I worry about a lot of local ground pet foods manufacturers adding TOO MUCH organ meat to their mixes to make it cheaper to manufacture. For reference organ meat should only be about 10% of the cat's overall diet, and only 5% of that should be liver (letting your cat eat too much liver over a long period of time can cause Vitamin A toxicity). The rest of your cat's diet should be to 80% muscle meat, and 10% bone. As well there is some debate as to whether grinding meat causes important nutrients to be lost/destroyed, which is why a lot of recipes for ground raw cat food include certain supplements. Taurine loss is an especially big concern, because taurine is a vital nutrient that cats cannot synthesis themselves (unlike dogs and humans!) and is thought to be destroyed when meat is ground.
Since you don't need to grind the food your cat eats if he's willing to chew his own food (which it seems he totally is!
) you don't have to give him the ground food at all. If you do decide to keep giving him the ground food I'd really suggest asking whoever makes it what EXACTLY is in it, and in what amounts
. They should be more than willing to tell you, but if they aren't it would make me highly suspicious of the product. Just my two cents!
If you want any more information on prey model feeding there's great info if you just search google for it (I'd link it here but I'm not sure what the forum policy is about that). This forum is a great resource as well - the people on here are really knowledgeable and friendly, so feel free to ask any questions you can think of! Good luck to you and your kitten-who-must-not-be-named