Ever wonder how a can of dog food with 8% Protein could possibly compare to the nutritional value of kibble at 30% Protein?
Why would anyone would want to pay for the high moisture (water) content of canned food instead of getting more of the meaty good stuff?
In fact, this 8% canned Protein actually is higher than the 30% kibble Protein.
Without a small bit of background, this could easily be dismissed as an “alternative fact.” Take a few moments to explore the full facts behind it, and you’ll never view it in the same way again. Plus, you’ll feel smarter. So let’s get started.
Find some common ground between your food forms
Every pet food, regardless of form (raw, canned, dehydrated, kibble, etc) will include Guaranteed Analysis (GA) numbers. We’ve talked about the limitations of GA numbers in a previous post, but they’re the best information we have for comparison purposes.
It’s easy to use them to compare two foods of the same form. An interim step is needed to level the field when comparing foods of different forms, like kibble to cans. This is where “Dry Matter” becomes important.
Dry Matter simply removes water content from published nutrient values
Once water is removed, different forms of food can be compared equally. We can’t accurately compare the nutritional content of canned food to kibble until both are converted to a Dry Matter Basis.
Finding the Dry Matter Basis (DMB) is ridiculously easy, but is a step often overlooked. There’s a “magic number” associated with this process and it’s very easy to find.
Simply subtract the Moisture content listed in the GA from 100%. You’ll use this “magic number” for the rest of your calculation to determine DMB of a nutrient.
Comparing Protein content is easy once you’ve found your magic number
Let’s say a canned food has 8% Protein and 78% Moisture. Your magic number will be 22 (100 minus 78).
Now simply divide your magic number into the Protein value. (8% Protein divided by 22% magic number). That gives us a DM Protein value of 36%.
If you prefer to be more mathematical about this, here’s the real formula:
Now things can get more interesting
Let’s compare the above canned food 8% Protein with kibble containing 30% Protein. The kibble has a Moisture content of 10%. Our magic number for the kibble is 90 (100 minus 10).
That means the DM Protein level is 30 divided by 90. The DMB calculation shows that the kibble has a 33% Protein content, less than the canned.
You can use your magic number to compare Fat as well. The steps are identical. Simply use the Fat values of each food instead of the Protein values in the GA.
Dry Matter Basis is not needed to calculate carbohydrate content
While some foods include carbohydrate content in their GA listing, most pet foods do not. You won’t need your new found math skills to reveal this hidden percentage. It just requires simple addition and subtraction.
All pet foods are made up of Protein, Moisture, Fat, Ash and Carbohydrates. (Ash is the residue of food remaining after combustion, primarily minerals.) The total of these values will equal 100%.
Since the values for Protein, Moisture and Fat are provided in the GA label, we need a value for Ash. Chances are, this will not appear on your food since it is not required to be listed. But never fear, there are average numbers that can be used for comparison purposes.
The average Ash content for a dry food is 7%. The average Ash content for a canned food is 1.5%.
Carb calculations are easy with this information
Simply add the Protein, Fat, Moisture and Ash numbers together. Subtract from 100 and that gives you the carbohydrate content of the food.
Do a few of these exercises using the pet food package(s) you have around the house. You may be surprised to discover how much carbohydrate is contained in your kibble!
Comparing food forms is easy with Dry Matter
Now that you understand how to level the playing field, you can easily compare apples to apples. You can also be confident in your comparison of apples to applesauce, or apples to apple chips.
Dry Matter Basis is the key to your comparisons. That magic number will help you look at different forms of food in a much more enlightened way!