What Is Dry Matter Basis and How to Calculate It

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Pet food comes with a ton of nutritional values and it may be difficult to tell which one is best or contains more essential nutrients than the other especially for the aim of comparisons.

 In order for manufacturers to effectively provide accurate information on guaranteed analysis for their pet food product there must be a conversion to dry matter, without this it would be impossible to make valid deductions.

What is referred to as “Dry Matter Basis”?

 As far as pet food is concerned there are usually three main nutrients that usually require a dry matter basis calculation and they are protein, fiber and fat.

The dry matter basis of pet food can be defined as the mass of nutrient with the complete absence of moisture.

This is to say that one can find the accurate amount of protein, fat, and fiber contained in the product when the moisture content of the food is completely eliminated. This is especially applicable for wet pet foods.

When you pick up a can of cat or dog food, the numbers that is reported as guaranteed analysis on the packaging is known as the “as fed basis” percentage.

To further expatiate, the “as fed basis” depicts the overall nutritional content inclusive of moisture. This number can be used to calculate the figures for dry matter basis in percentages.

This method allows us to make proper comparisons of the nutrient values of various products whether both products being compared are either wet foods or dry food versus wet food.

Why is Dry Matter Basis so Necessary?

Analysis on wet pet food and dry pet food has revealed that often times the amount of nutrients such as protein found in dry food is higher than that found in wet food.

What then does this mean? Do dry foods contain more protein than wet food? The answer is NO! Everything we need to know lies in the moisture difference.

 So, what happens when you heat up your pet food?

When you heat up your wet pet food the moisture content begins to reduce as it evaporates and consequently the protein percentage as well as fiber and fat increases.

This is why it would be unfair to make a decision based on guaranteed analysis while comparing wet food and dry food.

Calculating Dry matter Basis

The conversion of values from As Fed Basis to Dry Matter Basis is important and can easily be calculated using this simple formula,

calculating dry matter basis

The parameters represented in the equation can be explained as follows:

Quantity represents a given “as fed basis” percentage while Moisture is the given percentage reported on the wet food guaranteed analysis package space.

Here is an example of how to use this formula using one wet and one dry dog food products.

Guaranteed analysis on two dog food products using “As fed basis” percentage
  Blue Buffalo (Dry food) Canidae (wet food)
Protein 30% 9%
Moisture 10% 78%
Fiber 7% 1.5%
Fat 12% 6%

The table clearly represents the different in nutritional content between the Blue Buffalo dry food and the Canidae wet food. Now, let’s calculate for dry matter using the parameters of “as fed basis” available.

Blue Buffalo


These results are Dry matter values after the elimination of moisture content. The results can now be compared against one another to determine which pet food product has more nutritional content.

Guaranteed analysis- dry matter basis only
  Blue Buffalo (dry matter) Canidae (dry matter)
Protein 33.33% 40.91%
Moisture 0% 0%
Fiber 7.78% 6.82%
Fat 13.33% 27.27%

Results from the table shows that Canidae wet dog food dominates the Blue Buffalo dry food in protein and fat content by a significant margin whereas the Blue Buffalo has fiber advantage over Canidae. These calculations can be used for comparing the nutritional value of any two products.

But wait… there is one component missing from the mix… Ahh Carbohydrates!

Pet foods are mainly protein… very high levels of protein, so high that carbohydrates may seem insignificant but nonetheless we will have to cover this topic as well since carbohydrates still plays a valid role in providing energy for our pets.

In order to find the value for carbohydrates we must add one more parameter to the equation and that is “Ash”

What is the significance of Ash?

Ash is the product of complete combustion. When an organic material is burnt the dark remnant is called ash. It is composed of minerals such as Zinc, Calcium, Iron, Phosphorus, and others.

Dry pet foods always contain some element of ash in very small amounts even though ash content is usually not displayed on guaranteed analysis.

Some manufacturers may decide to display ash content on their product to make it easier to calculate Carbohydrate content.

 However, if Ash content is not displayed on product the Applied Veterinary Clinical Nutrition publication estimates an average of 2.5% ash content for wet canned food and 8% for dry pet food.  

Calculating for Carbohydrate Content

The total carbohydrate content in the product can be calculated by subtracting the dry mass content of Protein, Fiber, Fat, Moisture, and Ash by 100%.

This calculation is expressed below for both Blue Buffalo and Canidae.

Carbohydrate content in Blue Buffalo (wet food)

100% – 33.33 – 13.33 – 7.78 – 2.5 – 0 = 43.06% Carbohydrate

Carbohydrate content in Canidae (dry food)

100% – 40.91 – 27.27 – 6.82 – 8 – 0 = 17% Carbohydrate

The result shows that Blue Buffalo comes with 26.06% more Carbohydrate content than Canidae.


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