dry matter basis, some questions and confusion

I'm getting a headache trying to calculate dry matter basis from canned labels. I get the feeling that I am doing it wrong. My cats did not ask for a dunce mom. Please bear with me, for their sake. :rub:

Is there a pinned thread someplace on TCS that breaks down cat food labels and dry matter calculations in a way that the average 10-year-old child or mathematically challenged adult could understand? Maybe in the TCS resources thread, feline nutrition articles and threads? Nothing jumped out at me there but I don't always notice the totally obvious. :lol3:

If I have a canned cat food--Nature's Variety Instinct lamb, in this case--which gives the Guaranteed Analysis as:

Protein min 11%
Fat min 8.5%
Fiber max 3%
Moisture 75%

am I wrong that Dry Matter Basis values for that food would be:

Protein: 44%
Fat: 34%
Fiber: 12%

and the carbohydrate DMB content would be 10%?

Am I even close?

I'm also a math failure , but I came up with the same DMB using those numbers and the formula used by Dr. Pierson.

As far as I know there is no sticky for the calculations.

When I was feeding my crew canned food, I went through Dr. Piersons list of commercial foods (http://www.catinfo.org/docs/FoodChartPublic9-22-12.pdf), found the ones with low carbs, brought the list to the store. I really couldn't get my brain into doing math while shopping.

The DMB calculations off Guaranteed Analysis are not always accurate because of the min/max values issue plus ash and fiber are not always listed. Dr. Pierson's list on www.catinfo.org is more accurate, but not every food is listed.

There's an Excel file on http://catcentric.org/ that does the calculation for you.

Dr. Pierson's chart is the best to use, because she contacted all of the companies and the information presented is based on the average nutritional content of the food, not the guaranteed analysis - so it is FAR more accurate. Because the guaranteed analysis only lists minimums and maximums, it's possible to have a situation like with Weruva, where on a guaranteed analysis basis, one of the foods looks like it has something like 30% carbs, but on the average nutritional analysis basis (what's actually in the food), it has almost no carbs at all.

But there are a lot of foods not in her list. If you're looking things up while you have access to the internet, here is an online calculator: http://www.scheyderweb.com/cats/catfood.html

Or you can download one for Excel

2010 http://catcentric.org/wp-content/uploads/2011/10/DMB-Calculator.xlsx

1997 - 2007 versions of Excel: http://catcentric.org/wp-content/uploads/2012/01/Frankenprey-Calculator-Excel-97-2003.xls

Technically, ash should be included, as it is not part of the carb content. Sooooo many foods don't list the ash (minerals) though. In canned food, using 1.5% for ash is a good estimate, and for dry food, using 8% is a good estimate.