Comparing dog food brands on the basis of guaranteed analysis results in skewed and often inaccurate data. A more accurate way to compare pet food brands is on the basis of dry matter (DM) content.
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What is Dry Matter?
Dry matter is everything in the food except for the water content. This means that it includes all of the proteins, fats, carbohydrates, vitamins, minerals, and other nutrients. Most importantly for pet parents, dry matter basis is used to calculate calories.
To determine the dry matter percentage of any given pet food, simply subtract the moisture content from 100%. For example, a food with a moisture content of 78% has a dry matter percentage of 22%.
What is guaranteed analysis?
Guaranteed analysis is the minimum percentage of certain nutrients that are guaranteed to be present in the food. However, it’s important to note that the guaranteed analysis does not tell you the amount of dry matter in the food.
For example, a pet food may guarantee that it contains at least 18% protein and 5% fat. However, this food could actually contain more than 18% protein and 5% fat on a dry matter basis.
How to calculate guaranteed analysis:
You don’t really need to calculate guaranteed analysis as it is provided by dog food manufacturers. AAFCO requires all commercial dog food products have guaranteed analysis on their labels.
If you have dry matter basis and want to get the guaranteed analysis, you can use this formula:
Guaranteed Analysis = (Dry Matter Content/100) x Nutrient Percentage
For example, if a food has a dry matter content of 22% and is 18% protein on a dry matter basis, the guaranteed analysis for protein would be:
(22/100) x 18 = 3.96%
This means that the food must contain at least 3.96% protein according to its guaranteed analysis.
Why is Dry Matter Basis Important?
There are two main reasons why dry matter basis is important for pet parents to understand. First, it provides a more accurate way to compare pet food brands. This is because guaranteed analysis numbers are based on the as-fed basis, or the food in its wet state. This means that they include the water content of the food, which can be misleading.
Brand A and Brand B in the image below appear to have nutrients that are not very different but considering that Brand A has 2% moisture and Brand B has 30% moisture, the actual nutrient content in these foods is very different.
The second reason dry matter basis is important is because it allows you to calculate the calories in a food more accurately. This is because guaranteed analysis numbers do not take into account the water content of the food, which means they may be overestimating or underestimating the calorie content.
To calculate the calories per kilogram of dry matter, simply divide the guaranteed calories by the dry matter percentage. For example, a food with 400 calories per kilogram and a dry matter percentage of 22% has 1818 calories per kilogram of dry matter.
How to calculate Dry Matter Basis:
The easiest way to calculate dry matter basis is to use our Dry Matter Calculator. Just enter in the guaranteed analysis numbers and the moisture content of the food, and it will do the rest!
You can also calculate dry matter basis yourself by subtracting the moisture content from 100%. For example, a food with a moisture content of 78% has a dry matter percentage of 22%.
DMB% = AFB% * 100% / (100% - M%) ,
DMB% is the dry matter percentage,
AFB% is the as-fed basis percentage, and
M% is the moisture percentage.
For example, if a food has an as-fed protein content of 30% and a moisture content of 78%, the dry matter protein content would be: DMBprotein% = AFBprotein% * 100% / (100% – M%)
DMBprotein% = 30% * 100% / (100% – 78%)
DMBprotein% = 30% * 100% / 22%
DMBprotein% = 136.4%
This means that the food has almost 37% more protein on a dry matter basis than it does on an as-fed basis!
Keep in mind that these calculations will only be accurate if the moisture content is listed on the guaranteed analysis. If it is not, you can estimate the moisture content by assuming it is 50%. This is not an ideal way to calculate dry matter basis, but it will give you a general idea.
Once you have the dry matter percentage, you can then calculate the calories per kilogram of dry matter by dividing the guaranteed calories by the dry matter percentage. For example, a food with 400 calories per kilogram and a dry matter percentage of 22% has 1818 calories per kilogram of dry matter.
Dry Matter in Canned vs Dry Dog Food:
Canned dog food will always have a higher moisture content than dry food, which means that it will have a lower dry matter percentage. This is because canned food is typically around 78% moisture, while dry food is only around 10% moisture.
This can be confusing for pet parents because they may see that canned food has fewer calories than a dry food on an as-fed basis. However, when you compare the calories on a dry matter basis, you will see that the canned food actually has more calories. This is because there is less water in canned food, so the calories are more concentrated.
When comparing foods on a dry matter basis, it is important to make sure that you are using the same dry matter percentage. For example, if you are comparing a food that is 22% dry matter to a food that is 10% dry matter, you are not really comparing apples to apples. In this case, you would need to calculate the calories per kilogram of each food at the same dry matter percentage.