When comparing pet foods, have you noticed that the protein levels in a canned pet food always seem to appear lower than in a dry food? Looking at the label on a canned pet food, you’ll often see reported protein percentages below 10% while a dry kibble will report a much higher protein percentage. Does this mean there is less protein in wet foods? No it does not, the difference lies in the moisture.
Dry Matter Basis
The system used for reporting pet food percentages factors nutrient content on a "Dry Matter" (DM) Basis which is defined as “the amount of nutrients included in the food when the moisture content is factored out”. In other words, the widely varying amount of water present in different types of foods is not taken into consideration. This can be misleading when comparing the nutritional values of pet food, especially when comparing a wet or canned food to a dry kibble.
The only way to make meaningful comparisons of nutrient levels between a canned and dry pet food is to first remove 100 percent of the moisture content from each pet food being evaluated. This moisture-free approach to stating the true nutrient content of any food is known as dry matter basis.
To accurately determine the amount of a nutrient contained in a pet food, start by subtracting the moisture content (as listed on the label) from 100; the result will tell you what percentage of the food is Dry Matter. From there, simply divide the listed amount of the nutrient by the Dry Matter, then multiply the result by 100.
For instance, we are looking at this can of wet cat food to determine it's protein content as compared to this bag of dry cat food. The dry food reports 36% protein while the wet food reports only 11% protein. That is a significant difference but it is not the whole story - because the dry and wet food contain vastly different amounts of moisture.
The label on the dry food reports a minimum of 36% protein and 10% moisture. If we subtract 10% moisture from 100, we learn that the food is 90% Dry Matter. Then we can divide the 36% protein by the 90% Dry Matter and multiply the result by 100 to reveal that this dry cat food contains 40% protein.
The label on the canned food reports a minimum of 11% protein and 83% moisture. If we subtract 83% moisture from 100, we learn that the food is 17% Dry Matter. Then we can divide the 11% protein by the 17% Dry Matter and multiply the result by 100 to reveal that this cat food actually contains a whopping 64.7% protein!
This same formula can be used to determine percentage of any nutrient (e.g protein, fat, carbs) on the label and it works the same for dry, wet and raw pet food diets as well.
Of course, there is much more to pet food than numbers (numbers cannot reveal the true quality of the ingredients) but this little tidbit can come in handy when comparing different brands and types of food for your pet.
For a more visual explanation, check out this infographic we created comparing a canned dog food to a dry dog food that we sell at Downtown Tabby Pet Store. You can click the image below to enlarge or download the infograpahic.