You mentioned that you mix it with plain pellets. Why not just feed them the plain pellets?
Since you originally asked about the nutrients, and I didn't answer that part, let me address that now. After rereading the ingredients in that list you posted a link to, there are several things that I'm noticing. There are several corn products, including corn oil which is listed twice, lots of chemical additives, vitamin supplements that they don't need, artificial colors, and a lot of ground up produce that has probably lost most of it's nutritional value and just adds way too much sugar to the food. Basically, even though it doesn't have any seeds or nuts in it, this is really just high fat, pretty colored junk food for guinea pigs.