Guinea pig diet
The majority of guinea pig diets should be grass/hay and wild plants. Pellets should be viewed as an optional supplement, not a main food.
Guineas need to be provided with a variety of safe wild plants. Here are a few places that have great info (even though aimed at rabbits):
Additionally Guineas need foods rich in vit C, like bell peppers
The vast majority of pellets on the market have poor quality ingredients that contribute to gut problems and obesity. Pellets should not have ingredients like soybean hulls, wheat feed, soybean meal or molasses
We recommend cold pressed forage pellets such as Bunny Nature, Hay Box or Meadow Menu or to feed pellet-free. Grass pellets like Emerald Green can be a good supplement for outdoor guineas in the winter
Guineas love having a handful of Readigrass mixed in with their hay.
We buy our bales of Timothy Hay from https://www.timothyhay.co.uk/
We also love the Ings hay from https://www.hay-and-straw.co.uk/
It's also worth finding out if you have a local farm shop that sells bales of good quality hay (usually £6-8 for a big bale), this is much cheaper than buying small bags from pet shops. They'll also likely sell big bales of Readigrass/Graze On
Look for nice greenish sweet-smelling hay.
Plastic wrapped bags of hay from pet shops are usually not good enough for guineas to eat, they're often soft, chopped too short, brownish and the plastic wrap causes them to sweat and mould.