Hello,
In this forum there is some programs for balanced diet o feed formulation, i.e. FedSoft, Feed, o Excell work sheet by David Tish in your book: Animal Feeds and Nutrition and Ration Evaluation. Also you can consult NRC 2006, Nutrient Requirements of Dog and Cat. You can do a balanced diet with work sheet excell with funtion Solver.
Greetings!!!