Feeding your guinea pigs
Ours get treats of fresh vegetables every day (green peppers, lettuce, cabbage, cucumber etc.) and Timothy Hay based pellets. Most Importantly they eat lots of KMS Hayloft 2nd cut Timothy Hay. It is not just food, it helps keep their teeth healthy and it is lots of fun to run and jump into a big pile of hay. They also like to play hide and seek in it. The fibre is good for the gut. They eat only KMS Timothy Choice pellets because they're the best :-) Also given, every day, half of a 100mg Vitamin C tablet (that's 50mg per guinea pig per day!) of Wonder Laboratories product 0651/0652 (Qty 100 or 250). We used to use Puritans Pride Acerola with Vitamin C, however they drastically changed the formulation of their product and most guinea pigswould no longer eat them, probably because they put Sorbitol in them!! They tasted awful to us too. Ours couldn't even stand the smell. Guess they drove everybody away, because they no longer sell 100mg at all! We have tried GNC and American Health products and they won't eat them either, although we don't know why. Using Wonder Laboratories our guinea pigs love them, although a rabbit we know refused to eat those too. They call them 'Wafers', but they are very thick and need a pill cutter to prepare for use. By being thick, youngsters can even have mouths that are too small to eat them, in which case we break them down further into quarters (our female 'Honeydew' is still too small to eat 50mg chunks).
Our older friends, or if they are sick, eat Critical Care to get a real boost. Recently, on the advice of the Cambridge Cavy Trust, we have been using Critter Be Better from American Pet Diner. Oxbow products can often be bought from local feedstores..
What they CAN eat daily: Carrot, Cabbage, Celery, Apple, Grapes, Melon, Peach, Pineapple, Plums, Lettuce, Cucumber, Meadow Hay, any Guinea Pig pellets with NO Additives or colouring, Russell Rabbit Carrot and Leek (in UK), Pear, Banana, Orange, Radish, Broccoli, Cauliflower Leaf, Peas, Parsnips, Green/Red/Yellow Peppers, Tomatoes, Cherries, Grass, Com, Oats, Wheat. NOTE: when using grass, make sure no insecticide, herbicide or fertiliser has been sprayed on the grass!
Things you must NOT feed your guinea pig: Spinach, Chicory, Alfalfa Hay, Guinea Pig Mix with seeds or dried fruit, Basil, Swiss Chard, Water Cress, Sweet Clover Hay, Beetroot TOPS, RAW Potato, Rhubarb, Buttercups, Moss, Bindweed, Leaf or Flowers from Bulbs, Evergreens, Ragwort, Ferns. Anything spicy hot. This is not an exhaustive list. If in doubt, leave it out! Don't feed them nuts or seeds - these can cause dental and abcess problems (example - "wild" bird seed). If a pet store tries to sell you a salt (NaCl) block then tell them it most certainly is NOT required for guinea pigs. If you have one, or have been buying them, take them away from your guinea pig(s) NOW.
Water - Water and water "quality" are extremely important. High concentrations of minerals can cause kidney stones, most of which are calcium or phosphorus based. If your guinea pigs have a genetic history of stone formation (you have offspring from a previously affected pig), or if you are in doubt, it is best to use one gallon bottled water from stores such as Walmart/Neighborhood Market, Target, Publix, Ingles, etc. Make sure that the jug/bottle says "Reverse Osmosis" on it and not "tap water", "drinking water", "distilled water" etc. Clean your guninea pig water bottles regularly, using careful rinsing after the cleaning. Don't use water from store-based RO machines (refillable jugs/bottles) - these can be poorly maintained and of little to no use. If you want RO water for you, your family and guinea pigs, you can install an under-the-sink unit. Low cost, but harder maintenance systems from GE can be bought for as low as $150 from Home Depot, etc. A simple low work-load one at $250 is made by Watts. It can make 50 gallons per day, with a waste ratio of 2:1. Most guinea pigs (obviously depending on size) should drink between 1.4 fl.oz. (40 ml) to 3.2 fl.oz. (90 ml) per day each. In the USA, further guidance can be found at the USGS Water Quality web pages. The most important image is:
UK water hardness map
Light green=soft; Middle green=medium; Dark green=hard
You may want to try to find your own country's water hardness map.