Read this thread- especially the second portion of it.
http://www.guineapigcages.com/forum/...arts-info.html.
It's essential to feed veggies and a bit of fruit now and then to ensure that your pigs are getting the proper amount of C and all the other vitamins and minerals they need. If they do not get enough C (which they cannot make on their own) they can get a condition called scurvy. Scurvy, left untreated, can be fatal meaning they will die. The C that is in pellets (especially in low quality brands) doesn't last very long. If it's left exposed to light and air, it degrades much faster and you don't know how much C your pigs are getting per day. By feeding 1 cup of fresh veggies per pig per day, you are ensuring that your pigs are getting the required vitamin C dosage.
Also since cavies are constant grazers, it gives them something nutritious to eat besides hay. Pellets are the
least part of any cavies diet.
What brand of pellets do you feed your pigs?