With newborn b/f poo - I would just chuck the lot in the machine, do a prewash (with a teeny bit of powder) a 60 degree wash (with about 1/2 the amount of recommended powder), and an extra rinse. A couple of nappies would still have a bit of staining, but it always came out in the sun? Oh, and I use either Radiant, or Amolin. Whichever I grab first. LOL. I did find tho that my mum's toploader machine didn't clean the nappies as well as my frontloader, dunno what type of machine you have?

I found microfibre was notorious for staining.

Are you using liners? If you cut microfleece liners to cover the majority of the nappy, then not much poo should get through to it, making the washing more successful. Some were still so runny that they wet through the liner, but usually the liner catches it all.

HTH!