What you are doing now is fine the only thing that bothers me is .. Do you actually jog with him at 6 months of age? You should not be jogging him at this age.. I know you shouldnt run/jog a dog on hard surfaces until they are at least a year of age. I know a few on here disagree. But I am firm believer you need to allow the bones to grow properly w/o impact. I know you are probably asking yourself .. "well the dog runs" well there is a difference between him doing his own impact b/c he can justify when he should stop. When you are running/jogging with him.. "your goal" is more focused on yourself then your dogs body so you push the dog to run your distance and time. (saying this in general, not you persay)
Food, well you want to feed a low carb more protein diet no matter what food you feed. I am a big avocate of raw diet but there is excellent quality kibbles, good quailty kibbles, ok kibble and just plain garbage. but that is up to you on what you believe you dog should eat
Now suppliments: at this age you really need to just give him calicum w/ D, glucosamine w/ manganesium, fish oil and a multi vitamin
He is to young for the weight gainers.
He looks great now .. keep up the GREAT work
"In order to really enjoy a dog, one doesnt merely try to train him to be semi human. The point of it is to open oneself to the possibility of becoming partly a dog."