my ds was breast fed for 1st 6 weeks and is now bottle fed (11 weeks) but has always had a tendancy to only go every couple of days and when he goes boy does he go!!! Think it depends on the individual baby rather than how hes fed etc.
I b/f dd and she'd sometimes go 2 or 3 days without a poo. At most she did 1 a day. But that wasn't because she was constipated, a b/f councillor told me it's because they have little waste to pass out from breast milk so can often tend to do lots of small ones or infrequent larger ones.
I don't know anything about formula I'm afraid except I have heard it can lead to a bit of constipation.
It depends on the baby - DS1 and DS2 were both breastfed, and DS1 never went a day without pooing, but DS2 often goes a few days, up to seven, I think. DS2 is fatter, so it's not that he's not eating enough.
Kama, my ds3 is 15 weeks but should be only 8 weeks. up to 2 weeks ago he did several poos a day, now he does one HUGE one every 3-5 days, very messy! It is very unlikely that a breastfed baby would be constipated and so long as they have wet nappies and are gaining weight there is nothing to worry about.