For the dog there isn’t less protein in DUCK FOOD than in dry food but more because the quality of that protein is much higher. The amount only appears smaller if, as prescribed by law, it is expressed in %. A dog does not eat percentages, it eats amounts or grams!
When comparing the amount of protein in food, one should first deduct the moisture and then compare it with the dry substance. For protein, the biological value is much more important than the weight. You could compare this to a fruit salad. When opening such a can, you’ll see pieces of apple, pear, grapes, pineapple, etc. and with a little bit of imagination this is perfectly comparable to protein. Just as separate pieces of fruit together form a fruit salad, all separate amino-acids together from protein.
Let’s assume you have a dog that needs 140 grams of protein. If protein were a fruit salad, that dog would need exactly one can. But the problem is the balance of fruits. In every can of fruit salad, there are three red cherries and the dog needs nine of them. And there is the big difference between heated food such as canned and dry food and natural food, which must not be heated and thus is not damaged because it contains fresh meat and organs, and that is why dogs that do not eat natural food are too fat, and at the same time “undernourished”. This may seem a contradiction, but it isn’t because they’re trying to set off their deficiency of certain amino-acids by eating more, which makes them too fat, but there will still be a deficiency, resulting after a while in one or several disorders as described above in the table of problems induced by bad food.
Next to high temperatures, which are very damaging for proteins (and not only for proteins, also fats, vitamins and enzymes are damaged, destroyed or saturated), the selection of the food’s basic materials is also very significant for the protein quality.
Protein from soy can only be used for 45% of a dog’s total requirement. If we assume that a food contains 25% of protein and the source of protein is soy, then only 45% of this 25% is of use to a dog.