This might be interesting (if you aren’t doing it already).
A lot of material I use, I comb out the fur close to the skin first. You don’t need it to give your fly a better action and it absorbs a lot of water, making your fly heavier when wet.
And all the stuff I comb out, I collect into little jars, and use it as dubbing material.
Whether it's silver or artic fox,
or bunny zonker strips.
But also racoon, goat, yak…
And even some synthetic fibres, like this Polar Fibre.