It's important that you give the cats some type of fiber when feeding raw, other wise they will get constipated.
Some people use psyllium, but I think it is easier and safer to just add pumpkin or steamed winter squash, such as butternut or acorn. I rotate the other veggies, such as yams, carrots, the green veggies, etc. but even if i am just mixing a small batch, i always add a butternut squash.
I use a 85-90% meat/organ/bone mixture and then 10-15% veggies. So for every 10 pounds of meaty bone and organs, I add 1 to 1 1/2 pounds of veggies. Fully half that weight is in winter squash, the rest is other veggies.
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The squash is a fermentable fiber, so it's good for their digestion, as well as providing fiber to replace the hair and feathers they would get in whole prey. This will help keep them from getting constipated.
If you do use psyllium, be sure you give plenty of water, otherwise you can make the constipation worse. I just avoid the psyllium all together.