Another important calculation every owner should understand is how to compare the nutrient content between different diets. For instance, if you want to feed a diet that is low in fat – you need to know how to compare the crude fat on the guarantee analysis section of the label on different pet diets. If the diets contain different amounts of water – i.e. a canned diet vs. a dry diet – the fat content reported on the labels will always make the canned diet look like it is lower in fat. Why?
This is because crude fat and other nutrients are reported in what we call, “As Fed” – meaning how much fat is in a scoop of that food as it comes out of the bag or can. You need to know how much fat is in what we call “dry matter” or the percent fat in a diet after all the water is removed.
How do you figure crude fat on a dry matter basis to compare your different diets?
Here is an example for you to follow:
Diet A is a dry food with 10% moisture and 18% crude fat as fed
Diet B is canned with 75% moisture and 4% crude fat as fed
It looks here like Diet B would be the best “low fat” diet to feed, BUT do the math….
Diet A has 100- 10 or 90% (0.90) dry matter….what is left when water is all removed.
Diet B has 100- 75 or 25% (0.25) dry matter ….what is left when water is all removed.
You take the “As Fed” of crude fat and divide it by the dry matter or:
Diet A: 18% crude fat as fed divided by 0.90 = 20% crude fat in dry matter
Diet B: 4% crude fat as fed divided by 0.25 = 16% crude fat in dry matter
SOO – Diet B is the lower fat diet you want!!!
Now try doing the math for this example:
K9 Love MY Food Dry is 11% moisture, 20% crude protein, 16% crude fat – all as fed
Wolfing It Down Raw Diet is 75% moisture, 15% crude protein, 9% crude fat – all as fed
Which diet has highest protein? Lowest fat?
How do you compare them? Remember you have to convert to nutrients in the dry matter….
K9 Love MY Food Dry:
100- 11 = 89% dry matter (0.89)
20% crude protein as fed, but divide this by 0.89 dry matter or 22% protein in dry matter
16% crude fat as fed but divide this by 0.89 dry matter or 18% crude fat in dry matter
Wolfing It Diet:
100- 75% moisture = 25% dry matter (0.25)
15% crude protein divided by 0.25 dry matter is 60% crude protein in dry matter
9% crude fat divided by 0.25 dry matter is 36% crude fat in dry matter
K9 Love is 22% crude protein and 18% crude fat in dry matter or we would say “dry matter basis”
Wolfing It is 60% crude protein and 36% crude fat dry matter basis…
Now you can compare any diets by doing this simple math….