Hi!
A good diet and a MOT vet check from a preferably piggy savvy exotics vet is all your little one needs; the weight/growth will come on its own. Some shop babies are not big/old enough to be sold yet. Has your little baby got a companion to help it settle in? Guinea pigs are group animals and are not wired to be on their own. Especially young ones will feel very vulnerable and stressed without the protection of their mates and are much more likely to fall ill or not eat well.
http://www.guinealynx.info/companionship.html
A good diet should comprise:
- Unlimited hay (should may up to 80% of the dailt food intake). Vital for optimal gut movement and to keep the crucial back teeth ground down evenly. If your piggy is very young, you can additionally offer a handful of alfalfa hay daily. it is very protein and calcium rich and should not be fed past 4 months.
- unlimited good quality pellets (rather than muesli) until the weekly growth rate is slowing down somewhere between 4-9 months old, then reduce very gradually. Fully grown mature guinea pigs from about 12-15 months old need only about half to a handful of pellets.
- ca. 1 cupful of mixed veg, preferably containing one vitamin C rich veg like a slice of pepper, a bit of broccoli or a sprig of fresh coriander, parsley, dill, mint or basil. Please vary. Do not introduce more than veg at a time to a piggy that has not had any veg before and be patient and persistent. Fruit and tomatoes only twice weekly.
Here is a list of veg piggies can eat.
http://www.theguineapigforum.co.uk/showthread.php?t=42
- fresh water without any additives daily, as the water intake is very individual (but noticeably less when there is stuff in the water).
Please weigh your guinea pigs weekly, daily if they are not well. It is an important tool to notice problems early on when they are still easily treatable.
Here are tips on how to settle in shy new piggies that have not had much human contact. Please give your youngster a cuddly toy to snuggle up in until he has another piggy to live with.
http://www.theguineapigforum.co.uk/showthread.php?t=36239