HAU DOLCE
Dry matter in dog food
The content of a nutrient once water is taken out. The only fair way to compare wet and dry food, because a wet food label gives values diluted with water.
Dry matter is the most useful concept on a label that is not actually on the label.
Where the problem comes from
Wet food contains about 80% water, dry food about 8%. When you read ‘protein 8.2%’ on a tin and ‘protein 26%’ on a bag, you are not comparing quality - you are comparing water content.
The formula
Dry matter content = label value / (100 - moisture) x 100
Example
Wet food: protein 8.2%, fat 7.4%, moisture 80%.
- protein: 8.2 / (100 - 80) x 100 = 41% DM
- fat: 7.4 / (100 - 80) x 100 = 37% DM
The same food that looks poor on the tin turns out, once converted, to be high in protein. And the other way round: fat that looked innocent can be high once converted - which matters for a sensitive stomach and for dogs on a fat-restricted diet.
What to use it for
For comparing two foods with each other and for judging whether food described as easily digestible really has moderate fat. When working out portions, though, use calories, not percentages.