We feed 4-5 cups/day of Orijen Acana kibble + freeze dried raw, which is over the recommended by 2 cups. Our shepherd is/has/always will be underweight, but he's small-framed and tips the scales at 63 lbs.
A lot of that is due to conditions he endured until I got him as a 3 year old.
Orijen and Acana recommend 2.5 cups for a 88lb dog if I remember correctly (we dump the bags and use the airtight container for freshness), but again, it really boils down to:
-what your dog needs based on activity level; and
-your dog's appearance and whether or not it needs the extra calories.
Kaleef Black Bear Bugatti
CGC, Advanced Obedience, Intermediate Air Scent Tracking,
600+ trail miles
Jackson von der Rescue Farm (schnoodle)
75+ trail miles