The explanation is quite simple, and the reason is relatively similar to why baby humans require special food. The nutritional requirements of dogs change with age, and a puppy needs a different kind of food. An adult dog will stop growing while a puppy grows at a rapid pace.
Due to this rapid pace of growth, the biological needs of a puppy are entirely different. Your pup may need a different type of fuel to grow fast and strong. The amino acids, fats, and minerals are quite different from those present in adult products, so you should ensure that you feed your beloved pet the best food for Siberian husky puppy you can find.