my hamster died a couple weeks ago. and we have this bedding left over (hasn't been used at all)
Most bedding is designed to be used by many types of small animals, and aspen bedding shouldn't pose a problem for your new guinea pig. You can always pick another bedding product if you don't like how it performs. Enjoy your new pig!
I use fabric bedding for my piggie for her to be comfy when she goes to bed, some ppl do use wood shavings but, they would I have to be changed more often since they arent as absorbent
