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.
This is also the stage when dogs learn their social skills, so training and socialization is very important now. 2 - 5 years of age can be considered the young adult stage. This is the period of life when the dog has finished its growing and is active and healthy. Its diet should be of a maintenance type. 5 - 8 years of age is the equivalent to middle age. The dog begins to slow down and minor health concerns may start to crop up such as mild arthritis or heart murmurs. At this stage diet should be watched as some dogs have a tendency to become overweight.