Pups are almost 48 hours old. Their first poos were brown (normal) as the day has gone on they have turned a yellowy colour, little lose but not bad. Thay have gained weight are well and sucking.
The question is is it normal for their poos to change to this colour?
As said above, quite normal. The first poo you see from a pup, is the mekonium. That's what's been produced before birth. It's rather glue-like, and dark in colour. It's very important for the pup's ability to digest the milk, that the mekonium is passed.