is the European Pet Food Industry organisation. The website has plenty of information about feeding dogs and other pets. One document that I have just come across is FEDIAF Scientific Advisory Board Statement Nutrition of senior dogs.
There seems (to me) to be a move away from life stage foods, generic ones being quite popular especially at the quality end of the market. On page two of the five page document there is useful information about energy requirements of older dogs. However, they do say that currently there is no experimental data dealing with the energy requirements of older dogs. They reference a study in Labrador Retrievers which showed that a 25% restriction in food intake had positive effects on longevity and health.
There is some information about protein/fat etc on page 3. Interestingly, they say that protein levels should correspond to that of the adult dog to avoid loss of lean body mass. The older dog being fed smaller portions needs a higher quantity of good quality protein. From my experience of feeding a smaller quantity of food it is sometimes helpful to divide it into three meals to satisfy the dog’s hunger. Cooked, puréed vegetables might also be a useful adjunct to satisfy appetite.
The document is only five pages long and is not too scientific that it can’t be understood by the average pet owner. I found it interesting and useful.