If you want to compare feeds you have to call the company and request they email you a complete nutrient analysis of the food. Since fish require omega 3 fatty acids I think you should see this in the NA (I don't know if O-3 is listed on the bag because I've never bought a bag). A guaranteed analysis is shown on the bag for some components and this is different from the actual nutrient analysis.

You can figure out the carbohydrate content by adding the major components of the food (protein%, fat%, ash%, and moisture%) and subtracting from 100%. Ash content is something that companies don't always want to tell you but it can be significant (ie.10%), a higher Ash content indicates a lower quality food. Moisture will be around 10%.

Note: the protein percent in a NA is crude protein and not digestible protein and you can't distinguish how much of the total protein is attributed to animal sources vs. plant sources. Purina isn't fond of giving out technical information and they will often cop out and say "that's proprietary information" for certain things. (I have never been able to find out ethoxyquin levels from Purina.)

If you have trouble getting a complete Nutrient Analysis from a company there are labs that will analyze a food sample for you if you really want to know.

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