Energy is fuel for the body, it is used to maintain a constant body temperature, proper functioning of organs and muscle work. We provide it to animals in food in the form of proteins, fats and carbohydrates. The basic unit of energy is the calorie (cal), but in nutritional practice we most often use the kilocalorie (kcal).
In dietetics we use the term metabolic energy (ME), these are calories (net). Each meal in the bowl contains a certain amount of calories (gross), but the animal’s body never digests the meal 100%, some of the energy is always excreted, for example in the feces. Metabolic energy (ME) is the value, after deducting these losses, that the body will actually extract from a given portion of food. This is why ME is the most reliable indicator in dietetics. [1].)
Why do we count everything as 1000 kcal?
NRC [1] provides the requirement per 1000 kcal of metabolic energy (ME). Thanks to this, the standards set out in this way apply to both a tiny Yorkie, a giant Great Dane, and any cat. And although their portion sizes differ dramatically, the nutritional density of the diet remains comparable. At BARFLAB, we calculate the diet in exactly this way, so the results can be sensibly compared regardless of the species and size of the animal.
RER and MER - what do they mean?
Energy demand is usually calculated in two steps [2]:
- RER (Resting Energy Requirement) - jet is the energy needed for resting metabolism, which depends on body weight (to calculate it, the animal’s weight is raised to the power of 0.75 in dogs and 0.67 in cats).
- MER (Maintenance Energy Requirement) - this is the maintenance energy demand. We calculate it by multiplying the RER by the activity factor, life stage, neutering, etc. This is the final daily caloric intake that your pet needs.
At BARFLAB, we calculate the demand based on the animal’s profile (weight, activity, BCS) and based on this we select the appropriate calorie content. However, remember that the MER value should be treated as a starting point. This is only a formula to help you choose a dose, not a strict guideline. The most important thing is to observe the animal whether it is gaining weight (too many kcal) or losing weight (too few kcal) at this dose, and correct the dose if necessary.
Sources
- National Research Council (2006). Nutrient Requirements of Dogs and Cats. National Academies Press. https://nap.nationalacademies.org/catalog/10668/nutrient-requirements-of-dogs-and-cats
- Merck Veterinary Manual. Nutritional Requirements of Small Animals. https://www.merckvetmanual.com/management-and-nutrition/nutrition-small-animals/nutritional-requirements-of-small-animals