CALCULATION OF THE METABOLIZABLE ENERGY
OF A CATFOOD
When we speak about the energetic value of a food, it usually means the "metabolizable energy" (ME), or the available energy for the animal, once the fecal and urinary loss have been deducted.
This value depends on two main parameters : the digestibility and the fat content.
Influence of the digestibility
The National Research Council proposes 2 different equations for the calculation of the energetic value of dogfood, which are also usable for catfood.
1) NRC 1974
* (% CP) x 4 + (% CF) x 9 + (% NFE) x 4 = ME (kcal / 100 g)
* CP = Crude Protein ; CF = Crude Fat ; NFE = Nitrogen Free Extract ;
with % NFE = 100 - (moisture + CP + CF + Crude Fiber + Minerals).
To be consistent, this equation implies a high digestibility : it is the one used by Royal Canin to estimate the metabolizable energy content of Feline Nutrition and Felistar products (except Felistar S9), and its competitors.
2) NRC 1985
(% CP) x 3,5 + (% CF) x 8,5 + (% NFE) x 3,5 = ME (kcal / 100 g)
This second equation corresponds to products whose digestibility is medium. It is used for all other Royal Canin products than RCFI and Felistar.
Royal Canin checks the validity of these theoritical approximations by measuring the real digestibility of the foods. The difference between calculation and reality is very low.
Influence of the fat content
The Feline Nutrition Range now contains 7 different products, that contain from 10 % up to 23 % fat. Considering an increasing order of energetic concentrations, they can be classified so:
Slim 37 < Fit 32 < Kitten 34 < Hair & Skin 33 = Persian 30 < Sensible 33 = Senior 28.
A 4 kg cat requires 60 to 80 kcal/kg per day, or 60 to 80 g of Fit 32 per day.
Royal Canin strategy consists in proposing products that do not encourage energetic overconsumption.
On the contrary, our competitors propose very high fat diets that oblige owners to strictly check the consumption of their animals.
Donated by the Borg Cardona and Co. Ltd. visit Borg Cardona website