Ok, I am by no means an expert at this, so hopefully other people will chime in, but I'll see if I can be of any help.
I do agree with you about whole prey probably being the best from a nutritional standpoint, but from a convenience standpoint... not so much, at least for me
The problem isn't just finding a large enough variety with out breaking the bank, but actually convincing my cats to eat whole prey. It's taken several months just to get them on 100% raw.
What are your cats eating right now? Are they on kibble or canned food? Do they eat any raw at all at the moment? Do they hunt mice or birds or anything? My understanding is that dogs are usually much easier to transition to raw than cats are. Unless the cats are already used to raw meat and bones to a certain extent, they're going to need a transition period. I'm having the most trouble convincing mine to eat bones.
In any case, I'm assuming the chicken and turkey carcass you're getting will come with organs and everything included. That's really cool (I wish I could find something similar), but I'm not sure if only offering your pets two (or maybe three) meat and organ sources are enough variety. My understanding of whole prey or prey model (which is what I do) feeding is that feeding as much variety as you can is what enables you to avoid supplements. Just as an example, in my freezer I have 13 different kinds/cuts of muscle meat, two different kinds of liver, two different kinds of kidney, and two different kinds of bone (although my cats predominantly eat quail bones they're starting to eat chicken wings again). I'm not really satisfied they're getting enough organ variety, but I just haven't made it to the specialty butcher to look for more yet.
I should probably just repeat that I'm not an expert at this, and most of my research was into raw feeding cats, so I don't know if it's very different to feed dogs. I know cats need sources of taurine, because they can't synthesis it themselves - unlike dogs (and humans). Basically meat from hardworking muscles will have more taurine than other kinds of meat (i.e. chicken thigh has more taurine than chicken breast). All raw meat is higher in taurine than cooked meat, but dark meat, like chicken/turkey thighs/legs, and heart meat (what harder working muscle is there than the heart?) is very high in taurine.
That said, I'm still not sure why you want to stay away from red meat... Unless absolutely all red meat triggers the dog's digestive issues? In that case, you could try pork (my cats really, really love pork, surprisingly
), duck, quail. There's nothing saying you can't mix whole prey and prey model, if you have any concerns about your pets getting enough variety.
Personally with whole feeding chicken/turkey, I would also be a little worried about getting enough balance between the organ meat/muscle meat/bone since you're not actually feeding a whole carcass to each animal. For instance if you cut up the carcass and end up giving one cat mostly breast meat and one cat mostly dark meat for too long it's possible the cat eating mostly breast meat will become deficient in taurine. Or if one cat loves liver and ends up eating most of the liver every time you feed them, one cat could become deficient in vitamin A while the other gets vitamin A toxicity from eating too much of it. If you were feeding them size appropriate whole prey (like mice, rats, quail, chicks, small rabbits) they'd be eating the right portions of everything every time, but only feeding part of a carcass you'd have to try to keep track of this stuff to make sure each animal was getting enough and not too much of everything. I'm not really saying you can't do it, just I'm not sure if it's really the easiest way to keep everything balanced when feeding smaller animals like cats.
Oh and lastly, unless your cats are really experienced raw eaters with strong jaws, I don't know that they'll even be able to handle all the bones in a chicken. Unless they're experienced, cats that can eat chicken thigh bones and drumsticks, or even just the drumette part of a chicken wing, don't seem to be the norm. Most cat's can handle chicken ribs, wingettes and wing tips, and chicken necks. Mine can eat all the bones in a quail, but are taking their time working up to anything bigger. It's really all up to the individual cat's experience with raw bones and jaw strength. Most cats that eat predominantly kibble or canned food have weaker jaw muscles, which need time to strengthen before they can handle large bones.
Ok I apologize for this novel, and also if I just ended up repeating stuff you already know
Good luck with the raw food for the kitties, and don't hesitate to ask any other questions.