How to determine the carbohydrate content of commercial dog food

Carbohydrates are not measured directly, so you won’t see them listed on the label, but we can estimate them by subtracting the key information on the guaranteed analysis located on the pet food packet from 100.  Often a company won’t list the ‘ash’ value, but the general estimate for a kibble is between 5-8% (we have used 7% in our calculations).

Moist foods have lower ash values, usually around 2-3%. Some equations include fibre and some don’t. Because fibre is indigestible, it doesn’t really matter which approach you take as long as you’re consistent.

Guaranteed analyses are expressed on an “as fed” basis. However, to accurately determine what our dogs are eating, it’s important to convert these guarantees to a dry matter (DM) basis when comparing foods with differing moisture content (e.g., raw vs. dry foods).

 

Example

Popular commercial kibble product

Label guaranteed analysis (as fed)

Protein 27.0 %
Fat 12.0 %
Fibre 4.0 %
Moisture 12.0 %
Ash 7.0 %

 

Percent carbohydrate (as fed)                  =100 - % protein - % fat – fibre - % moisture - % ash

=100 – 27 – 12 – 4 – 12 – 7 = 38.0 % carbohydrate

 

But once we take out the moisture:

Percent carbohydrate (DM)                   =[Percent carbohydrate (as fed) ÷ (100 –moisture)] x 100

                                                                        =[38.0 % ÷ 88] x 100

                                                                        = 43.2 % carbohydrate

 

Big Dog Combo Raw Dog Food

Label guaranteed analysis (as fed)

Protein 13.0 %
Fat 13.7 %
Fibre 1.0 %
Moisture 69.0 %
Ash 2.4 %

 

Percent carbohydrate (as fed)                  =100 - % protein - % fat – fibre - % moisture - % ash

=100 – 13.0 – 13.7 – 1 – 69 – 2.4 = 0.9 % carbohydrate

 

Percent carbohydrate (DM)                   =[Percent carbohydrate ÷ (100 –moisture)] x 100

                                                                        =[0.9 % ÷ 31] x 100

                                                                        = 2.9 % carbohydrate

 

The same principles can be applied to other nutrients in our dog’s food in terms of converting them from ‘as fed’ to a ‘dry matter’ basis. For example, it may appear that the kibble is much higher in protein than the raw food, but once the moisture is removed, this is the more accurate representation of what your dog is eating:

Ingredient % (DM) Popular kibble Big Dog Combo Raw
Protein 30.68% 41.94%
Carbohydrate 43.2% 2.9%

If you’d like to have a look at this further, there’s a handy calculator to do some of the hard work for you, by helping you find the DM% of pet food. Find it at this link. Happy calculating!

If you’d like to know more about the common carbohydrates found in pet foods, read our guide here.

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