Here’s what I would do.
Isolate the cow in AE as you suggest. You don’t need the cow itself for the pIllusion emitter, but you need to be able to make the cow “disappear” after it explodes.
For the emitter, I would start with some existing explosion-type emitter. Something fast because the cow will be close to the camera I assume (as opposed to far off in the distance). I might even start with the “dust puff” emitter — don’t remember where it is. Change the color of the dust to red to turn it into a blood mist, then duplicate the particle type. This new particle type would then need the “cow chunks” images imported, probably increase the velocity, play with the size and weight parameters…
There’s a similar thing in the “making a frog go poof” tutorial. The AVI link is broken in that tutorial, but you can see the finished movie on our gallery page.
Alan.
wondertouch