Don't give Crisco.  In the first place oils slow things up in the digestive
tract because they are harder to digest.  In the second place, there have
been cases in the medical literature of ferrets who were given
polyunsaturated oils -- regularly -- which developed severe nutritional
disorders.  Have not read of any ferret problems yet with monosaturated oils
or with saturated ones.
[Posted in FML issue 2180]