Weaning is the process of teaching three to four week old puppies about eating solid food instead of depending exclusively on their dam's milk.  Just as with human babies, puppies reach a point where formula (mother's milk) alone cannot provide all of their nutritional needs.  This weaning process should not be rushed, or handled in a slap-hazard manner.
     Many times puppies will begin to experiment with their mother's food when she is fed.  If a breeder/owner observes this, this is one signal to start getting serious about teaching the puppies to eat out of a pan.  There are many dog people who simply allow the pups to learn through observing their mother and experimenting on their own how to eat.  Unfortunately, there are two major objections to this method.  Some dams will snarl and snap at the pups for taking, or attempting to take, her food.  This does not help the learning process.  The other objection is that the food the adult dam is eating is not the food that will satisfy the nutritional needs of the puppies.  The digestive system of puppies is simply not ready for this quantum leap.  The easy way is not always the right way.  In this case, it could lead to malnourished and underdeveloped pups.
     There are several commercial dam's milk replacements available and when mixed with a good to excellent dry puppy food, to the consistency of loose oatmeal, makes a good starter.  Gradually reduce the milk replacement with water, and make the gruel thicker until the puppies, reaching the age of six or seven weeks, will be eating only solid food.
     One process that helps the individual puppy to learn to pan feed,  is to place a pan of gruel in a safe area and place one puppy by the pan.  The reason we say one puppy is that, when it's an all-the-gang, free-for-all feeding frenzy, the weak and the shy, or less dominant, puppies always get left out, and may even become malnourished.  By teaching one puppy at a time, you accomplish several tasks: social contact between owner and puppy is established, the puppy recognizes where the food is coming from, and the breeder/owner can keep track of how much each pup is eating, and also, note how smart, or slow-witted, the individual pups are.
     While the puppy is learning to pan feed, the scene can be hilarious.  When you have placed the pup by the pan of food, gently stick the pup's muzzle in the gruel.  Please don't immerse the pup's nose in the food, as he could aspirate the food into his lungs. The first time a pup feels milk, it can be somewhat of a shock.  This may have to be repeated several times, until the pup gets the idea.  Before long, he'll be splashing, experimenting and licking the food, and making a general mess of himself.  After a few minutes, pick the puppy up, clean and dry him, and put him back with his litter mates.  Then repeat the process with the next one until all have had a turn.
     One hint that you may find helpful, is to remember that the puppies are used to the dam lying on her side, with the milk source elevated.  If the puppies seem to display confusion in that they know the food is there, but where?  You may want to put some gruel on your finger, letting the pups lick your finger as you draw the pups attention downward toward the pan.

Supplements

     If you are using a good to excellent dry puppy food, you will not need to add any supplements to the pup's food.  It is important that a veterinarian is being seen by the dam and puppies on a regular basis.  If there are any vitamins, or mineral supplements needed the veterinarian will be able to tell you the exact reason and the exact amount to be added to the puppy's feed.  Adding supplements on your own can do more harm than good.  Where one imbalance may exist, by guessing which supplement is needed, you may be causing a second or third imbalance, due to how minerals are dependent on the proportion and amount of other minerals being present.