We have 2 black labs now, 6 month old Raven gets adult Pro Plan chicken and rice, the same as most of the dogs in the dog guide program she is a part of. 9 year old Sampson recently had to retire as a dog guide and now lives with us. He continues getting Pro plan. I am familiar with the feeding practices of a number of service dog programs. They all feed one or another of the common brands and make an early switch to adult food to control growth to give the developing joints more time to develop under less stress. For the same reason, they are very insistent on keeping the puppies lean.
The dog forums are dominated by those advocating premium brands. They go on and on about the ingredients and have no data relating ingredients to the health of the dogs. I think they are all a bunch of food kooks, food reps, and Kool-ade drinkers. I am widely despised for my factual posts.