I'm copying this from a lady on the dog board I help mod - great info on dog food.
I tend to get lots of questions about dogfoods, so I thought Id post some basics for reading and understanding ingredients lists. There is good information out there on this topic, but there are a few tips that everyone should know that are easy to follow.
Some companies are more forthright than others in listing their ingredients, so knowing some of the basics will help you get through the list without being bamboozled or confused.
Generally, you want to read through the ingredients carefully until you get to the first fat/oil listed. Ingredients listed before this make up the bulk of the food, and those listed after are included in much smaller amounts for flavoring, preservative value, to provide trace minerals, etc. There are some key things to look for among those top ingredients.
First, dogs are carnivores, so the meat is by far the most important ingredient in your dogs food. You want to see specific animals rather than generic terms listed as the sources of protein (chicken/lamb/bison not animal/meat /poultry). Meal form is preferred, because it means it is weighed after the moisture has already been removed. You want to avoid foods with byproduct listed in the ingredients, because this pretty much means anything left after all the stuff that is fit for human consumption has been removed.
Let me clarify . . .
chicken meal = excellent
chicken = good
poultry = bad, because it is unidentifiable
chicken byproduct = crap
poultry byproduct = unidentifiable crap
poultry byproduct meal = unidentifiable crap in concentrated form
Second, if your food contains grain (most does), you want to check for both the type and form of the grain. Rice is generally the most digestible grain. Oats and barley are also OK. Corn is the least digestible. Other than corn, wheat is the grain most likely to cause problems because many dogs are allergic. So, generally rice is best, but not all rice is the same. Like your mother told you, brown rice is healthier than white rice. Ground or meal form is fine, but stay away from other forms of processing because any nutritional value is lost. A common ingredient is brewers rice which simply means the crap left over from the brewery after weve gotten anything worthwhile out of that rice. Stay away from that.
Third, anything that sounds mysterious on your list of ingredients is probably something the manufacturer doesnt want you to know about. For example, stay away from foods with animal fat or animal digest these are unidentifiable ingredients and often contain rendered animals, which can be diseased animals, animals that died before slaughter, roadkill, and euthanized pets from animal shelters. Eeeeewww!
Finally, anything that sounds like it isnt good for your dog probably isnt good for your dog. Stay away from lard or sweeteners (often used for flavoring). Stay away from foods with lots of grains listed among the first ingredients or several variations of the same grain listed early in the list (for example, ground rice, brewers rice, and rice flour . . . can you say "filler). Also stay away from menadione (a vitamin supplement that may cause health problems).
I hope this helps. For a far more thorough and authoritative explanation, I suggest you visit
http://dogfoodproject.com/ This post is really intended for those who dont have the time or inclination to sift through all the content on that site. It is definitely worth a read if you do have the time.