Before I go through the trouble of grinding them. What's everyones preferred method of using them. Drop one down hole whole or grinding the with added ingredients.

I prefer grinding and preserving fresh.

Secondary ingredients seem to always greatly increase the attractiveness for me though in some special cases natural maybe needed.

Freeze, then grind. Once you have ground them you can then decide what to do with them; preserve “fresh”, age to desired level of taint, add ingredients, wait to add ingredients, options are endless. Keep in mind that preservatives in the right amount typically do not stop the decomposition immediately. I use salt for stopping the decomposition process, it takes days to fully stop.

I use fresh frozen whole and when I make dirthole sets I just drop the frozen mouse down the dirthole. I trap a bunch of mice throughout the year and freeze one or two to a sandwich size ziplock and I keep a couple coffee cans in my fur freezer the baggies and mice go into those cans. When setting I just grab a can or two and head out.
I don’t start trapping here until December 1st and ground is usually fairly cold by then. Haven’t tried preserving or grinding them up I just use whole frozen for each set.
One of my favorite baits at dirthole sets in low grazed pastures and hay meadows.
Jim

Grind with added ingredients.

I made a mouse bait, several years ago, that has outperformed any canine bait I have used since 1979. But, I only use it in one specific set.

Sold all my trapping stuff, but I still have several pints...lol

For the dirt hole

Never had much luck with it.

I still have several gallons of prepped bases of varying stages of juicy I haven’t done anything with in years.

Spouse modifies the ones he catches and uses them down the hole.

I love them under jugs for Catfish!