Feeding Guideline for English Mastiff puppy

Question
QUESTION: My male English mastiff is 5 months old (77lb), and is scheduled to be neutered at around 6 months. My question I have is about feeding.
A week ago, we decided to switch his dog food from bil.jac and is now feeding him Canidae All life stages dog food. We've been trying to follow the feeding guidelines for him, but he seems to still be hungry (6 cups). His last 2 ribs are visible, so I know he's not overfed for now. But can I increase the amount to feed him? Also, the feeding guideline for puppies only go up to 6 months. I hear people talk about english mastiff being puppies for 2 years. So, when do I switch his food portion to adult requirements? Sorry if this is repetitive, but I looked to see if anyone else has asked the question, and didn't find any.
Thank you in advanced for your help!

ANSWER: I would check the actual percent calcium in the Canidae.  Go to their website or customer service number.  it may be higher than the guaranteed minimum on the bag.  You don't want the calcium to be over 1.5%.  If it is, I would find an adult or ALS chow that isn't, perhaps going back to the Bil Jac.  There is no evidence that Canidae or other premium brands provide superior nutrition.  They just have ingredients that sound better to many.  

The early switch to adult food is becoming more common.  It is a well proven technique in the service dog programs and likely even more important for your Mastiff and other larger breeds.  It slows growth, allowing the joints to develop under less stress.  You just have to watch which adult chow and its calcium level.  

For the same reason you want to keep the puppy lean.  However, not so lean the ribs show much.  Go ahead and feed a little more.  Each dog is different. Standard recommendations are a good place to start, but each dog must have its food and exercise adjusted to its individual needs. Here is a link to a good illustrated guide, http://www.longliveyourdog.com/twoplus/RateYourDog.aspx

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QUESTION: Thanks for your quick response!

What is the concern in feeding dog food that is too high a percentage of calcium? It was analyzed at 1.8%, with a 1.2% minimum. Main reason for the switch is because my dog just does not like Bil.Jac at all. We ended up having to mix Bil.Jac with something so that he would eat it. Bil.Jac is actually more expensive than the Canidae I switched to.

So, back to my main question, on the feeding chart, it says as a puppy, he is to be fed 5-6 cups for puppies between 75 to 100lb. My mastiff is now 77lb and eating about 6-6.5 cups. I read their rule of thumb is to feed 1 cup for every 25 lbs, doubling it for puppies. My main question is when should I stop "doubling" it and switching to adult portions instead? Thanks!

Answer
Calcium is tricky.  Growing puppies must have it, but too much or in the wrong ratio to phosphorous interferes with the body utilizing what it needs.  Adults can excrete the excess, but not younger puppies.  I would look around for another food.  I know Iams, Pro Plan, and Science Diet are good.  None of the premium foods have the same track record.  They may or may not be OK.

You cut back on how much when the ribs start to become a little harder to feel as in the link I gave you.  Often that is 7-8 months for Labs, perhaps later for a larger dog that grows longer.  I feel that is part of why people say neutering causes a dog to get fat.  Neuter it a 6 months and continue to feed the same amount after growth slows, and by a year it is too fat.  Most of the puppies we have raised weren't spay/neutered until after a year old.