It is imperative to get this right. The puppies need a high fat food while they are developing in mom. This is important to ask a breeder. What did you feed mom while the puppies where developing? The pup is being constructed in it's mother with the nutrition it is being given so the result of your dogs health depends on genetics and nutrition. Skimping on either is just asking for problems down the road. In summary, feed a high fat food for the first 12 weeks after they are born and while they are in mommy.
The next phase is critical. After 12 weeks they need a food with a lower protein. Why? Because they will grow too fast. They will already grow at an accelerated pace just because they are mastiffs so you really need to keep this in check for the next two years.
Many think that their mastiff will get bigger if they feed it more protein. Mistake. Genetics primarily determine size with good nutrition practices. Too much protein can cause big irreversible problems during their growth phase.
Currently we like Holistic Select for Large Breed Puppies. But remember, pet foods are getting bought up left and right and most times they dilute the ingredients or eliminate some altogether. Things are always changing in the pet food business. We sell hundreds of thousands of dollars in pet food in our 4,000sf pet department at our hardware store and keeping track of all the foods is a challenge.
When they are two years old we love Acana. It contains "prey meats" which is the entire animal. Wolves eat the entire catch. The organs have minerals and micro nutrients that you cannot get anywhere else.
Also, research reveals that cancer cannot thrive in an alkaline environment. There is only one food that I know of that has a PH of over 7 and that is Canine Caviar. We mix this with Acana after they reach two years old to help limit the acidic environment in their bodies and thus helps keep cancer at bay.
Remember, cheap food has cheap preservatives which are known to be carcinogens. Ethoxquine is one such culprit. Plus you have to feed twice as much.
Saw dust has 12% protein so be careful. Know where the protein derived.
Also, you need clinical levels of glucosamine and chondroitin after two years old. It really helps them live a long and active life. 1200 milligrams a serving is ideal but anything over 800 will do.
Think of nutrition as a savings account. Good nutrition is stored in the bones and marrow. It can then be utilized later in life when it is needed.