[Calorie Content] Allometric Feeding Equations

Hey all, bit of a technical problem here.

Found a very good meta-analysis for the energy requirements of dogs (Link: Energy Requirements of Adult Dogs: A Meta-Analysis).

However I’m struggling to understand the significance of the two equations they use to determine these energy requirements.

These equations are:

  • kcal.kgBW-1.day-1
  • kcal.kgBW-0.75.day-1

I understand what they mean. For example, 81 kcal.kgBW-1.day-1 means that 81 calories (kcal) are needed for every kilogram of bodyweight (kgBW) per day, whereas 81 kcal.kgBW-0.75.day-1 means that 81 calories (kcal) are needed for every kilogram of bodyweight (kgBW) to the power of 0.75 per day.

My issue is with kgBW-0.75. Why is 0.75 power used?

Any help would be greatly appreciated, thanks in advance.

Unfortunately I cannot help you with this as it is beyond my knowledge/understanding. Hopefully someone who can assist will spot your thread and reply. If not, David keeps an eye on his Facebook page so you might want to post the question on there.

Thanks a lot for the help, will definitely check out that book and David’s FB page! :slight_smile: :slight_smile:

If anyone is interested I’ve copied an excerpt from ‘Canine and Feline Nutrition’ below which explains this issue :smiley:

“Formulating an exact equation to estimate the energy requirements of dogs is a difficult task because of the wide variety of body sizes and weights in this species. The amount of energy that is used by the body is correlated with total body surface area. Body surface area per unit of weight decreases as animals increase in size. As a result, the energy requirements of animals with widely differing weights are not well correlated with BW; they are more closely related to BW raised to a specified power [emphasis added]. This unit of BW is called metabolic body weight. Representing weight as metabolic body weight helps to account for differences in body surface area between animals of varying sizes. Historically, coefficient values used with dogs have ranged between 0.67 and 0.88.”

To summarise, the BW0.75 is just the standard coefficient value used in order to better correlate Body Weight with energy requirements.

Thanks for that Meg, I had found it before but never really looked at it - was stuck under a pile of research ::slight_smile: