Hi Sally - I don't see an article linked

They used to not give premmie babies pain relief for even quite major procedures, because they decided they didn't feel pain. Then further research showed that that is not true, they express it differently - so many babies must have experienced horrors

. So I don't think it likely that under 7 days lambs
feel pain any differently to when they're older, although they may appear to react differently.
The thing with tiny bits is that initially the ring doesn't fit, so they won't feel much. Surely any pain comes when the band is tight, on larger lambs or on older tiny lambs, irrespective of their age, up to a certain point? I wonder if the 7 day rule was arrived at as the result of good research, or just a general approach?