Bedding for Guinea Pigs?

I have recently brought two guinea pigs. I also brought a new hutch, I spread newspaper throughout the whole thing and placed hay on top of the newspaper in their bedroom. I have to change it every 2 or 3 days as it gets smelly due to their businessess that they leave behind. I was wondering if there is anything that I can put in the hutch so that I dont have to change it so often, eg wood shavings.