Hi yevincent –
Yes – calcium needs to be converted to a dry matter basis for wet foods due to the high moisture content. Calculating calcium levels on a kcal. basis (versus percent of weight basis) is the most accurate way to evaluate the appropriateness of foods as it accounts for varying caloric densities between different foods. For a large breed puppy you’d want to feed a food with 3.5 g. calcium per 1,000 kcal. or less. I’ll walk you through the calculation. Let’s say the food comes in a standard 13.2 oz. can, has 400 kcal. per can and the company tells you there is 0.3% calcium on an as-fed basis.
1) Convert 13.2 oz. to grams (easier to perform calculations using grams): (13.2 oz.)(28 grams/1 oz.) = ~397 g.
2) Calculate how many grams of calcium are in the can of food: (397 g.)(0.003) = 1.19 g. calcium per can.
3) Calculate how many grams of calcium per 1,000 kcal.: (1.19 g. calcium per can)/(400 kcal. per can) = 0.00298 g. calcium per kcal. (0.00298 g. calcium per kcal.)(1,000 kcal.) = ~2.98 g. calcium per 1,000 kcal.
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If you wanted the calcium level on a percent basis:
1) 100% – % Moisture = % Dry Matter
2) [(As Fed Calcium %)/(% Dry Matter)] X 100%
BTW – I’d highly recommend Tripett as a canned topper for large breed puppies. It’s not a complete and balanced food as it’s green tripe only but it makes a great topper if you’re feeding a balanced kibble. Green tripe is high in protein and naturally has a balanced calcium to phosphorus ratio but contains very low levels of each (only about 0.3% calcium on a dry matter basis if I recall correctly). The best part is dogs go nuts for it.
