Please don’t give it at all. You will not find any long term UK based owners who ever supplement.
It seems to be something that is done in the US but our forum advice is always against it.
(Supplementation may be needed during a period of illness to boost the immune system but it should only be done as a short two week course )
They get all their needs from a varied and balanced diet. Giving supplementary vitamin c above and beyond their dietary needs can actually become harmful.
First, excess vit c is simply excreted in the urine so at best you’re wasting your money by giving it to them.
Beyond that, supplemented piggies bodies become used to artificially and unnecessarily high amounts. If that level then drops even a little bit (if you forget to give it etc) even though their levels would still be well beyond any non-supplemented piggy, you will cause your piggies to get scurvy.
Scurvy is actually very rare in well kept piggies and it doesn’t come up often at all (a couple of times a year at most). In the cases which do crop up on here they either in rescue piggies who are neglect cases or in well loved piggies who have been supplemented with vit c but the supplementation has caused them to become unwell
