You want your puppy to grow into a healthy adult dog, so feeding him the appropriate dog food for his age is important. There is a difference between puppy and adult food because puppies are growing rapidly. Their needs are different than the adult dog that has reached his height and weight.
Proteins are the building blocks for the tissues and are necessary for a puppy's development. During growth, protein is essential for the development of muscles, internal organs, the immune system, digestive system and endocrine system. The highest amount of protein requirements are from birth to 4 months old. According to the Association of American Feed Control Officials (AAFCO), a puppy needs a minimum of 22 percent protein. An adult dog needs a minimum of 18 percent protein, so puppy foods usually contain more protein than adult food.
A puppy has twice the energy needs of an adult dog. For example, a 10-pound puppy needs 990 calories a day and a 10-pound active adult dog needs 404 calories, according to the National Academies. Carbohydrates are a direct supply of energy, and carbohydrates prevent the body from using protein for additional energy. Fats are the most concentrated source of energy. The AAFCO requires that puppy food have at least eight percent fat; whereas, adult food is required to have a minimum of five percent fat.
Calcium is a mineral and is crucial for the development of strong bones and teeth. However, too much calcium can cause skeletal abnormalities in some dogs, especially large breeds and not enough calcium can cause bone loss. Puppy food contains more calcium than adult food to aid in the development of the puppy's skeletal bone structure and teeth. The AAFCO calcium requirement for puppy food is 1 percent. For adult food, the requirement is 0.6 percent.
Puppy food is more nutrient dense than adult food. If an adult dog is fed puppy food, he is most likely going to gain weight and may develop orthopedic problems. The development of most dogs to their adult size is between 10 months to two years. Your veterinarian or your breeder can recommend the best time to switch to adult food. Usually the switch to adult food is when the puppy is close to his adult height.