Trial and error -- that's our experience. My wife and I got a female soft coated wheaten terrier puppy from a breeder. The breeder had been using grain free Precise Naturals. Our puppy doesn't eat more than necessary, but, even so, it seemed to us that she did't care for her food. Using the internet, I researched alternative food as best as I could. My focus was on food that was made in America and contained no ingredients from China. I even sent emails to manufacturers to ask about those two issues. Blue Buffalo seemed to be a top quality food -- it was prevalent in stores, on the internet, and more expensive than other foods. However, the email reply I received turned me off -- instead of replying "yes" or "no", it sent me a lengthy "lawyer's letter" containing a lot of ifs, ands, and buts. My internet search also revealed that, in lawsuits against it, its defense is that it didn't make the food (a manufacturer it hired made the food). So, I decided against Blue Buffalo. Then I found Merrick, and liked that it is clear about being made in America and having no ingredients from China (not even additives).
We began with Merrick Classic. Our puppy liked it. However, we noticed that she developed an itchy butt and erratic bowels movements (all formed, but the timing was off). Then we switched to Merrick Grain Free. Our puppy liked it. However, we noticed that she became lethargic (unusual for a soft coated wheaten terrier puppy, not yet spayed), and she became disinterested in her food. Then we decided to mix Merrick Classic with Merick Grain Free (50/50). Time will tell how this mixture works out, but for now it seems just right. Our puppy once again is playful and spirited, and her bowel movements seem appropriate.
Our thoughts are that every puppy is different, just as every baby is different. I have healthy twin grandsons, yet their food preferences and allergies vary. Our puppy's vet seems to agree, even though she's not definitive about the issue, and she probably would be happy if we bought food she sells (not Merrick).
Probably what's true is that there are a lot of fine choices on the market. Just experiment, to find out what works best for your puppy. And, if you agree with me, don't put any food from China in your puppy's mouth. I don't dislike China, but I don't think there's any dispute about the fact that its food and health regulations fall short.
Deboned Chicken, Chicken Meal, Potatoes, Peas, Sweet Potatoes, Natural Pork Flavor, Potato Protein, Chicken Fat (preserved with mixed tocopherols), Natural Chicken Flavor, Deboned Salmon, Apples, Blueberries, Yeast Culture, Organic Alfalfa, Flaxseed Oil, Potassium Chloride, Salmon Oil, Salt, Minerals (Zinc Amino Acid Complex, Zinc Sulfate, Iron Amino Acid Complex, Manganese Amino Acid Complex, Copper Amino Acid Complex, Potassium Iodide, Cobalt Amino Acid Complex, Sodium Selenite), Vitamins (Vitamin E Supplement, Vitamin A Supplement, Vitamin B12 Supplement, d-Calcium Pantothenate, Vitamin D3 Supplement, Niacin, Riboflavin Supplement, Biotin, Pyridoxine Hydrochloride, Folic Acid, Thiamine Mononitrate), Choline Chloride, Yucca Schidigera Extract, Dried Lactobacillus plantarum Fermentation Product, Dried Lactobacillus casei Fermentation Product, Dried Enterococcus faecium Fermentation Product, Dried Lactobacillus acidophilus Fermentation Product.
