The wiki page you're reading is probably wrong. It doesn't cite a source for its information. There aren't any sources in 5th edition D&D that help us find the answer (the Monster Manual has nothing of note about silver dragon diets), so I've dug through older fluff to get a picture of what a silver dragon eats:
The Draconomicon, a 3.5 sourcebook, has this to say about dragon diet on page 10:
Dragons are carnivores and top predators, though in practice they are omnivorous
and eat almost anything if necessary. A dragon can literally eat rock or dirt and survive. Some dragons, particularly the metallic ones, subsist primarily on inorganic fare. Such dining habits, however, are cultural in origin.
Unfortunately for a dragon’s neighbors, the difference between how much a dragon
must eat and how much it is able to eat is vast. Most dragons can easily consume half their own weight in meat every day, and many gladly do so if sufficient prey is available. Even after habitual gorging, a dragon seldom gets fat. Instead, it converts its food into elemental energy and stores it for later use. Much of this stored energy is expended on breath weapons and on the numerous growth spurts (see below) that a dragon experiences throughout its life
In 4th edition, they expanded the information slightly. In Draconomicon: Chromatic Dragons, the diet of a dragon is elaborated on page 12, noting that while they can eat anything, minerals, dirt, and the like are not very nutritious, so it has to eat a lot more than normal if it subsists entirely on inorganic material ("at least as much as its own body weight per day to maintain health"). If a dragon is eating actual organic food, particularly meat, then it needs to eat about 15-20% of its body weight per day to stay healthy and keep growing. It also says that in order for a dragon to become overweight, it has to eat a significantly larger amount of food (with an anecdote about an obese dragon that ate twice its body weight in food each day).
In Draconomicon: Metallic Dragons, it's also stated that eating the metal of a dragon's type helps promote scale growth and regrowth.
Also, while it doesn't have much about the feeding of baby dragons, I would greatly recommend trying to get your hands on Dragon Magazine #320, for the article on page 46, "Dragons: The Perilous Burden." It's got a details on the mindset of a young dragon and what they normally experience when fostered with humanoids.