I have been the owner of a Rottweiler for 2 years and I myself can already make a whole guide on its nutrition. I would advise you first to get acquainted with the dietary needs of different breeds of dogs A site I use for my dog is very well written about rottweiler food, and there is also a comparison of different brands of products. Do not forget to distinguish between puppies and adult animals.
Link to site removed by moderator.
I want to start a small business related to dog food. What questions for you as owners are relevant and what is missing in ordinary online stores?