Basal Energy Requirements (BER) = the amount of energy required by a healthy animal in a thermoneutral environment, while awake but not exercising, 12 hours after eating.
Resting Energy Requirement (RER) = The RER differs from the BER as it includes energy expended for recovery from physical activity and feeding, and is calculated from these equations dependent upon the weight of the animal. The RER for dogs and cats can be calculated with these two formulas:
RER (kcal/day) = 70(BWkg)0.75 (if body weight (BW) is less than 2kg). Calculation of this equation can be achieved with the use of a smartphone calculator (with the phone turned horizontally), a scientific calculator, or by using RER = (BWkg x BWkg x BWkg, √, √ ) x 70
It has been calculated that RER may be 1.25 BER, yet many texts often regard the two as interchangeable values.
Maintenance Energy Requirements (MER) = the energy required for a moderately active adult in a thermoneutral environment. This includes energy for obtaining, digesting, and absorbing food in animals to maintain optimal body weight. Average values for dogs are 2 x RER, while cats are 1.4 x RER.
Daily Energy Requirement (DER) = The DER represents the average daily energy requirement for any animal, dependent on life stage and activity. The DER is calculated from the RER and a life stage factor.
Neutered dog = 1.6 x RER
Entire (Intact) dog = 1.8 x RER
Active/Working = 3 – 8 x RER
Pregnancy >21d = 3 x RER
Lactation = 4 – 8 x RER (dependent on number of nursing puppies).