UPDATE: January 2016 - This post is several years old. I have been feeding a raw diet for nearly 5 years now and it is in my opinion the best thing I could ever do for my dogs. If you are looking for advice or opinions on a specific brand of food please follow the protocol I set forth in the blog post Choosing a Top Quality Dry Food or visit dogfoodadvisor.com to find out the specific rating of a food. I have fed raw so long I can't comment on any one food other than what is outlined in my articles and at dogfoodadvisor.com When it comes to feeing your puppy, try to feed them 3 to 4 times a day until your pup reaches 3-4 months of age, and then advance them to twice a day. Your puppy will indicate to you how much you should be feeding them. You can start with the guide below, but if your puppy eats the recommended amount of feed within a reasonable time, 20 minutes or so, then increase the feeding 1-cup at a time. 4-8 weeks of age 3-4 cups per day spread between 3-4 meals 8-12 weeks 4-6 cups per day spread between 3-4 meals 12-16 weeks 6-8 cups per day spread between 3-4 meals 4 to 6 months 8-10 cups per day spread between 2-3 meals 6-18 months 8-12 cups per day spread between 2-3 meals It is also important to remember how prone to bloat Mastiffs are. I don’t feel comfortable feeding more than about 3 ½ cups in one sitting to help keep the risk to a minimum. Also be sure to keep you puppy or dog from guzzling water after a meal. A drink is fine, but don’t let them drain the dish, you don’t want all that dehydrated kibble expanding too quickly in their gut. Make sure you puppy has access to fresh clean water at all times. Water should NEVER be withheld to aid in potty training. The only time my dogs or puppies do not have access to water is when they are crated, and for very young puppies this should be for short amounts of time only. When choosing a food for your puppy, make sure to feed a quality kibble with no by-products or added chemicals. It is also good to go ahead and start your puppy on adult food, not puppy food (your vet may argue with this, but they aren’t giant breed specialists, remember these aren’t large breed dogs, they are giant breed dogs). Most puppy foods have protein levels that are too high for giant breeds that grow so rapidly. You want your protein level to be right around 25% and absolutely no higher than 28%. It is also important to keep your calcium/phosphorus ratio right at 1:1. Doing these things is a huge step in preventing conditions like HOD (Hypertrophic Osteodystrophy) or Panosteitis. These are both painful conditions and can be crippling for life if not treated with a balanced diet. Remember, the size of your Mastiff is genetic, not nutritional. You cannot hurt your puppy by keeping him lean and fit, but overfeeding a Mastiff puppy can ruin them orthopedically for life, causing a lot of pain and numerous vet bills over the life of your Mastiff.