Maybe not the hooves, but if it's small prey (mice, small birds) I'm pretttty sure they would eat the fur and feathers. It's a great source of fiber!
Just to clarify my question, though, I was just wondering if supplementation was needed for raw that doesn't include the entire animal. For example, grinding chicken thighs and bones (with organ) like Dr. Pierson's recipe, or even not grinding those things, I would "think" needs some sort of supplements because of what's not being included (e.g. the parts I mentioned in my earlier post).
You have to consider what percentage of the entire meal those "extras" really make up.
Cats don't eat
all the feathers, nor even
all the fur from their prey. A lot depends on the size of the prey. With larger prey, often times the only thing left of a cat's kill is a skull and pile of feathers/fur too big to bother with. Very small prey, on the other hand, might be swallowed whole.
The percentage of
consumed fur/feathers/eyeball/brain is approximately 1-2%... in a 2.5 ounce meal, that would be .025 - .05 ounces. The nutrients involved in this percentage are miniscule; fiber is not something I'd count as "nutritional value".
Again, as long as you are feeding a
variety of food sources, supplements are not going to make that big of a difference. At least, not to the extent that a lot of supplement companies would like you to believe.
It's fine if you want to supplement occasionally, if that makes you feel safer, but I don't think it needs to be done every day with every meal.
.