Estimation of maintenance energy requirements in German shepherd and Labrador retriever dogs in Bangalore, India
Metabolisable energy defines the amount of food energy that is available for utilisation by the body following digestion and absorption, plus losses in urine and faeces, and equates to energy expenditure. It is the value used to calculate and express energy requirements for growth, maintenance of adult body weight, physical activity, gestation and lactation in dogs as well as cats.
Estimation of canine ME requirements is complicated by the great diversity in size, shape and body weight, which may range from 1 to 90 kgs or more, between dog breeds. Studies in animals varying in size from mice to elephants have shown that energy requirements are not related directly to body weight, but are more closely related to body weight raised to some power (i.e., BWx, also referred to as metabolic body weight; Brody, Proctor, & Ashworth, 1934). There has been considerable debate as to which power value best describes the relationship between body mass and energy requirement in dogs. Figures of between 0.64 and 0.88 have been proposed (Burger & Johnson, 1991), with current consensus being that 0.75 is the most appropriate estimate (National Research Council (NRC), 2006).
Mean estimates of maintenance energy requirements (MERs) for adult dogs, which reflect an individual's utilisation of energy for thermoregulation, metabolic processes and spontaneous activity, have ranged from 94 to 183 kcal/kg BW0.75 (Patil & Bisby, 2001). Factors that influence MER, and thereby account for this variation, include breed, gender, age, lean body mass, activity and environmental temperature. As a guide, the NRC's Ad Hoc Committee on Dog and Cat Nutrition currently suggests a MER of 130 kcal/kg BW0.75 for moderately active pet dogs (NRC, 2006).
Several methods have been employed to calculate MERs in dogs, including direct and indirect calorimetry, double‐labelled water and other stable isotope washout techniques, as well as digestibility studies and feeding trials where ME intake is calculated from a diet history or weighed record (Hill, 2006). None of these methods are universally ideal. Calorimetry and isotope washout studies are accurate but are expensive in terms of equipment and analytical costs, thus restricting their use to laboratory or experimental situations. Feeding trials arguably provide the best means of assessing energy requirements of free‐living pets, but rely upon accuracy in recording food intakes and determining the ME content of the foods consumed, which has limited their contribution to assessing canine MER.
The present study was designed to determine the MER of free‐living adult pet German shepherd and Labrador retriever dogs using a prospective in‐home feeding trial and was conducted in the Indian city of Bangalore. The study design also allowed for the assessment of how MER was influenced by breed, gender, body condition score and activity level.