I'm trying to solve my problem that I've found trying to find the best dog food. It's about ingredients of some dog foods made by good brands.
For example let's take a food brand which advertises itself as 75% meat and 25% vegetables. It's labelled as follows:
40% chicken meat, 30% chicken meat meal, potatoes, 5% chicken fat.
Calculated potatoes = 100 - 40 - 30 - 5 = 25%
35% crude protein, 16% crude fat, 10% crude ash, 2% fibre, moisture 10%
100 - 35 - 16 - 10 - 2 - 10 = 27%
It is a hypothetical dog food, but reflects the problem. For simplicity I omit losses of macronutrients during production process (i.e. extrusion).
The ingredient list is based on mixing bowl principle as we can read in FEDIAF labelling guide.
So in mixing bowl we have:
40% of chicken meat: 20% of protein, 4% fat, 2% ash, 76% water
30% of chicken meat meal: 65% of protein, 16% fat, 13% ash, 6% water
25% potatoes which has 2% of protein, 16% carbs, 2% fibre, 3% ash, 77% water
5% of fat which is 100% of fat
in a final product with 10% moisture we should have:
51.7% crude protein, 21% crude fat, 0.9% fibre, 8.9% ash, 7.4% carbs (the carbs we can also calculate, it will give us the same value)
BUT on the label we have different values! 27% of carbs, as calculated, come from 25% of potatoes! While it should be around 7.4%. And there is 17% less protein, and 5% less fat
I'm quite sure my calculations are correct because it works with almost 90% of foods of different types, dry, semi moist, home made, BARF...
What's the cause if this difference? I know there are ranges of tolerance of analytical constituents, but this is far off the tolerances. If all off the nutrients would be at upper range of tolerance, it would be about 13% less carbs (=14%) which is still 2 times more than expected.
Maybe the reason is the quality of used meat (for example with with bones) that raises the true value of ash to 20-30%? I doubt. These are well known brands. Maybe the dog food mislabelled?
The analytical constituents reflects ingredients like it was without 30% chicken meat meal and 55% of potatoes...
What do you think?