Compare dry and wet food - here’s how!
As mentioned before, the difference in water content between dry and wet food makes it difficult to compare nutrient content such as the protein content. A meaningful comparison can only be made by determining the ‘dry material’ (DM) – that is, the quantity of nutrients in the substance in a 100% dry state.
This sample calculation shows how the nutrient contents can be compared.
Compare the protein content of two renal diet foods – A (dry food) and B (wet food)
Renal diet A (dry food) contains:
10% moisture, 12.5% crude protein. 100% Original food - 10% water = 90% DM.
12.5 (crude protein) : 90 (DM) x 100 = 13.8% crude protein in the DM
Renal diet B (wet food) contains:
61% moisture with 6.8% crude protein. 100% Original food - 61% water = 39% DM.
6.8 (crude protein) : 39 (DM) x 100 = 17.4% crude protein in the DM
The example shows that the wet food clearly contains more protein than it appears to at first sight. It is therefore important to carry out the appropriate conversion if you wish to compare wet and dry food.