Life stages refers to the various developmental stages of an animals life. For dogs it means puppy, adult, senior and for some dogs a lower calorie diet for inactive or overweight pets. An adult formula contains moderate amounts of these nutrients. Senior diets generally contain less fat and fewer calories than adult diets but are often fortified with extra vitamins and minerals. Lastly diets for overweight or inactive pets contain more fiber and less fat and calories than the adult diet.
Some people leave food out all day long for their dog.
Dry pet food can be left out all day as long as your dog does not overeat and gain excessive weight. Even when given food all day, most dogs will generally only eat once or twice a day. However if your pet gains too much weight, it's a good idea to feed your dog using discrete meals once or twice a day. Once your dog adjusts to a particular food, the dog's system, including the bacteria that live in the gastrointestinal, establish a careful balance. Because different foods contain different ingredients and nutrients, too quick a change can upset his system.