hi, my name is Ang and I have a dane as well, his name is Sanity. (And one of my best friends has a deaf white dane who's Sanity's best buddy.) I've never heard of Blue Buffalo before. I'll have to look that up for you.Â
 Basically with a Dane puppy you feed them adult food (Preferably anything 24% protien or under) and avoid foods with fillers. I can give you a list if you'd like.
Edited to add I found this list I did on another post.
Well *Cracks fingers in preparation for a long typing session*
I note Alternative protiens for dogs with allergic reactions to some traditional protein sources.
I like Canidae. Depending on where you live you can get a 40 pound bag for $30-$35. It has a high calorie content, so you feed fewer cups. (24% protein)
http://www.canidae.com/dogs/all_life_stages/dry.htmlSolid Gold makes a food called "Wolf King", with Bison and Salmon as protein sources (22% Protein). Do not confuse this with "Wolf Cub" the puppy formula (26% protein)
http://solidgoldhealth.com/products/showproduct.php?id=62&code=170Fromm Four Star is a food that looks good on paper and I was about to try before I found the food that works for my dog (More on that later) They have several alternative protein formulas. (23%-24% protein)
http://www.frommfamily.com/products_fourstardry.aspEagle Pack has a Giant breed puppy food that's acceptable. (23% Protein) I also like their Holistic chicken (24% Protein)
http://www.eaglepack.com/pages/for_your_dog.htmlMerrick has several good formulas, however if your dog has a tendency towards gassiness I would stay away. Their alternative protein food is the Wilderness Blend and Turducken (24% Protein for both). They also have Cowboy Cook out (22% Protein) and Grammy's Pot Pie (23% Protein)
http://www.merrickpetcare.com/store/dry_dog_food.phpWellness is another dog food to avoid if your dog has gassiness or loose stools. Their Fish and Sweet Potato (22% Protein) is an alternative protein, and their chicken is supposed to be good as well (22%).
http://www.oldmotherhubbard.com/dogs/dry_intro.asp?pCode=dryAs for foods to avoid. Cindy talked about Innova EVO, don't get me wrong I LOVE this food, it's what I feed my Dane, HOWEVER the Protein is 42%, so it should NEVER be fed to puppies! EVER EVER EVER!
Avoid anything with fillers, ie corn, rice, grains, as the first few ingredients.
Avoid Lamb food for puppies as the LACK of Taurine can give them health issues.
I hope I haven't overwhelmed you, and feel free to contact me with questions!
Ang. The Food nut