Formula to help compare different foods nutrient values

by Shisa Wed Mar 11, 2015 12:49 pm

Helps you figure out how to compare nutrients based on the info on the label and how to compare between dry and canned food.
A bit simplistically put but I'll copy as it's written.

DRY MATTER COMPARISON:

" In order for us to do a dry matter comparison, we must first calculate how much dry matter there is in a food. Let us look at a 100g can of dog food:
The label tells us that the can contains 70% moisture.
This means that is contains 30% dry matter.
That means 30g of the 100g is dry matter (30%)
The 'as fed' label states that the can contains 10% protein.
The can is 100g meaning 10g is protein.
If we remove the water there is still 10% protein but it is present in the 30g dry matter.
This means that the the dry matter content of protein is:
(10÷30)x100= 33.3%

The equation used to calculate the dry matter content of a nutrient looks like this:
%nutrient divided by %dry matter multiplied by 100 equals %nutrient on a dry matter basis
(%nutrient ÷ %dry matter) x 100 = %nutrient on a dry matter basis

Now compare a dry product to the canned product.

The dry product contains 22% protein on a 'as fed' basis. To the pet owner this means that the dry food contains more protein (10% on the canned product).
The label on the dry product does not state any moisture. We assume 10% as legally moisture only needs to be stated if above 14%.
If 10% is moisture only 90% is dry matter.
In 100g of dry food there is 22g of protein, removing the moisture means 22g protein in 90g dry matter.
For this food the dry matter content of protein is:
(22÷90)x100 = 24%

Therefore the canned product has 33% protein compared to the 24% of the dry product although from the labels the dry food looked to have more protein in!"