Hi, my boy's number twos are always good and firm but on occasion, they are covered in a slimey mucus.  Is this normal?

Yes - it's the bowels reaction to something that has irritated it - wheat is often the cause - but if it happens regularly it may be worth having a word with you vet as it can indicate a problem with the bowel.

mine gets that sometimes, when she gets colitis we add a tablespoon of bran into her feed and a different vegetable (vets advice to me) and it works everytime for us.

It's probably not more than once a week and he goes twice a day.  It will only be there once and then disappears for a while.    His food is wheat/gluton free and I normally add a little tuna, scrambled egg or chicken to it.  I have a feeling that it might be the chicken but it's not all the time so it's had to say exactly what causes it. 

You could try leaving out the chicken for a couple of weeks then reintroduce it and watch for any reaction. :)

Kath.