My 5 year old setter eats 1x/day in evening, 1/2 can Purina Focus (wet) mixed with 1 full cup Purina Sport Performance 30/20. During hunting season he'll get an extra 1/2 to 1 cup of dry at meal time. Never feed my dog in morning of a hunt or during field trial training.
For those that feed their dogs grain free you may want to read this article -
https://todaysveterinarypractice.com...l%20PLOS%20ONE.