Water & Nutrients. Like humans and animals, plants need both water and nutrients (food) to survive. Most all plants use water to carry moisture and nutrients back and forth between the roots and leaves. Water, as well as nutrients, is normally taken up through the roots from the soil.
Changing from puppy food to adult food depends on the size of your dog as an adult. If he is a small breed and will not exceed 30 pounds, he is mature at 10 to 12 months old. Some small breeds are mature before 10 months of age. Medium breeds are dogs that do not exceed 80 pounds at full growth.
There is some variation, however. Large and giant breed dogs are considered puppies until two years of age, while some toy breeds are considered to be adults at nine months of age. Introducing Adult Food. Puppies are growing and developing every day, and require a food that meets those high-energy demands.