So I have been looking at websites and here also, about puppy growth rate chart. But did not come across a better answer as it is pretty aparent that not all puppies will follow the chart. Agreed. Now my question is, my showline puppy who will be turning 9 month old in next 2 weeks is just 53.8 lbs. I am feeding him Nature's Select 3-3.25 cups a day. I am switching to Orijen this week.
Each dog is different, even within the same litter. You are better to go by sight. From the top, you should see a gentle waist. From the side, in a standing position, you should barely. See the last rib, maybe 2. ------ Also, every kibble is different; amount you feed with one may not be the same for another. Start with the chart on the bag for the age, go by sight and adjust as needed.
Case for each dog is different. ------- I have two from Rose's litter. Both are on the same kibble. One eats 5 cups, the other eats 4. Both would love to eat more, but human mother knows best. They are 23 weeks old.
It also depends on their body type/bone structure. Some dogs have heavier bone structure and will be bigger dogs at maturity. Some are "finer-boned" so will weigh less. To me, that sounds awful small for a 9 month old male, how tall is he at the withers?
Could you post a picture of him, perhaps? While just under 54 pounds DOES sound awfully lightweight for a 9 month old GSD, if he's only meant to be a 65# adult by structure, then his present weight doesn't sound off at all. All depends on how he's built, what kind of bone structure he has, etc.
Sometimes people forget they are not supposed to be huge 110lbs dogs. So taking the breed standard for what it says the adult range is 77lbs to 95lbs.
If they assume 12 mos is adult that is 6.4lbs per month of age on the low end.
If they assume 12 mos is adult that is 7.9lbs per month of age on the high end.
Your dog at 9 mos and 53.8lbs is 5.97 lbs per month of age. So based on this 12 month average your dog is .43lbs to light on the low end. Not to far behind the low end of the breed standard.
Personally I would (and I think you do to) would like to see him around 63lbs at his current age. If your certain he does not have any parasites or anything and is healthy I would think your own the right track going to a food that will put some weight on him. Just change it over slowly.