The Standard Schnauzer diet will need to include animal proteins and healthy carbs, vitamins and minerals, and omega fatty acids--nutrients every dog needs to maintain its health in the long term. This means the best Schnauzer food is premium dry kibble, as it contains balanced portions of the above-listed ingredients. If consistently fed a premium brand like Royal Canin, Schnauzer dogs will be much healthier and longer-living.
And how much to feed a Schnauzer? Adult portions of dog food for Schnauzers is about 2½ cups of dry food per day, divided into two meals. Standard Schnauzer puppy food portions are a bit smaller: depending on age, about 1¾ cups per day, divided into three meals (not two) until six months of age.
For more info on Schnauzer dog food portions, here's a handy Standard Schnauzer feeding guide:
Dog AgeDog WeightFood TypeAmountFrequency2 Months8 lbsDry (Puppy formula)0.25 cups3x/day3 Months15 lbsDry0.4 cups3x/day6 Months25 lbsDry0.6 cups3x/day9 Months32 lbsDry* (Puppy/Adult)1 cup2x/day12 Months+40 lbsDry (Adult formula)1.25 cups2x/day*--Around this time, transition to adult food by mixing in adult formula with the puppy formula, in slowly increasing amounts with each meal, for one week.
Try if possible to stick to the above-listed portions. Though not really pone to obesity, if these dogs are constantly overfed (and under-exercised) they certainly can become overweight--and a fat Schnauzer will have numerous health problems and a potentially shortened lifespan. You can help control your Standard Schnauzer's weight by having 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.
If you're worried your Standard Schnauzer is overweight, try this simple test: run a hand along the dog's side, and if you can't feel any ribs, it's diet time--which means less food and more exercise!