Like that of all breeds--and maybe even more so than most for these athletic dogs--the Irish Setter diet will need to include plenty of animal proteins and carbohydrates for energy, vitamins and minerals for digestive and immune health, and omega fatty acids for coat and skin wellness. This means the best Irish Setter food type is premium dry kibble, particularly the kind made for active breeds. This high-quality food, while more expensive and difficult to obtain, has balanced portions of the above-listed nutrients that will maintain the dog's health in the long term. Cheap, generic food is not recommended for this breed, because it usually consists of mostly empty "filler" ingredients that are unhealthy, are harder for the dog to digest, and may even shorten its lifespan if eaten on a consistent basis.
Merrick, Royal Canin, and Taste of the Wild are three recommended brands that carry excellent lines of premium dry food for active breeds.
And how much will an Irish Setter eat each day? The typical adult, depending on its age, size, and activity level, will need about three cups of premium food per day, divided into two meals. Irish Setter puppies will eat less: again depending on age, they'll need about two cups per day, divided into three meals (not two) until six months old. For more info on feeding an Irish Setter from puppyhood through maturity, see this feeding chart:
Irish Setter Feeding ChartDog AgeDog WeightFood TypeAmountFrequency2 Months10 lbsDry(Puppy formula)0.3 cups3x/day3 Months18 lbsDry0.5 cups3x/day6 Months35 lbsDry0.7 cups3x/day9 Months50 lbsDry* (Puppy/Adult)1.25 cups2x/day12 Months+65 lbsDry (Adult formula)1.5 cups2x/day*--Around this time, transition to adult food by first mixing in a bit of adult formula with the puppy formula. Over the course of a week, with each meal add a bit more adult food to the mixture, until the dog is eating it entirely.
If possible, try and stick to the above-listed portions. If constantly overfed (and under-exercised), these dogs might become overweight--and a fat Irish Setter will have joint, breathing, and digestive problems, not to mention a potentially shortened lifespan. You can help control your Irish's weight by establishing consistent feeding and exercise schedules, by not feeding the dog table scraps, and by not leaving food in the dog's bowl all the time, thereby allowing it to eat anytime it wants. It's better to put the dog's bowl down only at mealtimes, then pick it up a few minutes after the dog begins eating.
If you're worried your Irish Setter is overweight, give the dog this simple test: run a hand along its side, and if you can't feel any ribs, it's diet time. Reduce the dog's daily food consumption by one-fourth, and add an extra walk, jog, bike ride, or play period to its daily exercise schedule.