Royal Canin Nutritional Information

Royal Canin Nutritional Information

The Labrador has a greater fat mass than other dogs of similar weight.
The Labrador is one of the breeds at risk of developing obesity. (© Hermeline).

Key Points to Remember:

When Estimating the Energy Need of a Dog in Good Physical Condition

There are many equations that attempt to describe the determina-tion of energy need as a function of weight. In the canine species, the body weight range is so wide that the maintenance energy require-ment (MER) cannot be directly expressed as a function of body weight (BW): a 50-kg dog clearly consumes less than two 25-kg dogs. The MER must be calculated on the basis of metabolic weight, using an allometric equation of the type:
Maintenance energy requirement (MER) = a x Body Weight (kg) b
(kcal of metabolizable energy / day).

The problem is inherent in the evaluation of coefficients a and b, and the results differ slightly depending on the experimental conditions and the size of the groups: a few examples are shown in the table below.

Figure 12. Development of the maintenance energy requirement depending on weight according to different authors.

The differences in the results are often clearer as the weight increases. In the literature, the most frequently used equation is given by the NRC 1974. It represents a good compromise between the various equations proposed. No single mathematical model is truly satisfactory. Indeed, even at a constant weight, the energy requirement varies considerably according to age, breed, sexual status, climate conditions, level of activity and lean body mass. For an equal weight, the maintenance requirement of two dogs can vary depending on their body composition.

Whatever the basis used for the calculation, it is only a starting point: the precise adaptation of intake to actual energy expenditure can only be realized based on observation of fluctuations in body weight and body condition score. The MER actually varies considerably from one individual to another. While it is sometimes difficult to weigh a large-breed dog when it has reached its adult weight, there are parameters that allow its physical condition to be estimated. Ideally, the ribs and the vertebral column are not visible, but easily palpable, and the waist is also clearly discernable.

Key Points to Remember:

In the Estimation of the Energy Value of the Food

In its 1974 and 1985 editions, the NRC proposed two different equa-tions for calculating the metaboli-zable energy (ME) value of a food:

1. Equation proposed by the NRC in 1974 for the calculation of the energy for simple ingredients (also known as the Atwater equation). This equation has been used in human nutrition since 1902.

ME (kcal/100 g) = (4 x % proteins) + (9 x % fats) + (4 x % nitrogen-free extract*).

2. Equation advised by the NRC in 1985 (modified Atwater equation)

ME (kcal/100 g) = (3.5 x % proteins) + (8.5 x % fats) + (3.5 x % nitrogen-free extract*)
* Nitrogen-free extract (NFE) rough-ly represents total digestible carbo-hydrate. It is obtained by the difference:
NFA = 100 - (% moisture + % protein + % fat + % mineral + % crude fiber)
The differences between the coeffi-cients used reflect the different hypotheses with respect to the digestibility of the categories of nutrients:
-The Atwater equation estimates the digestibility of protein at 91%, and those of fat and NFE at 96%.
-The modified Atwater equation estimates the digestibility of pro-tein, fat and NFE at 80%, 90% and 85%, respectively.

What is the best equation?

The ideal equation depends on the dietary content, as shown by the graph below, which compares the energy value measured and the theoretical energy value calculated with the two equations.
-The Atwater equation gives values close to the values measured, albeit slightly overestimated, when the food contains low levels of fiber and is consequently characterized by high digestibility.
-The modified Atwater equation is a better reflection of the reality in the case of food containing a high level of fiber that is consequently characterized by low to medium digestibility.

Figure 13. Correlation between calculated and measured metabolizable energy.  

French Mastiff puppy. (© Hermeline)

Conclusion

The lowest metabolizable energy level of a food is the value obtained after digestibility measurements are taken in dogs. In the absence of measured values, the Atwater equation should be reserved for highly digestible foods and home-prepared diets.

The daily ration for a dog is obtained by dividing the daily energy requirement by the metabolizable energy value of the food.