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Educational Note
Achieving Energy Balance Behind some of the top-performing dogs in the country are owners who understand the dynamics of energy balance and body condition, and who have successfully matched their dogs' energy needs with their energy intakes. Canine clinical nutritionists say tile best way to achieve energy balance is to start by following the feeding guidelines printed on a dog food package, and then to use a body condition score system and a dog's weight to help determine whether a food adjustment is needed. Kathryn Michel, D.V.M., M.S., assistant professor of nutrition at the University of Pennsylvania School of Veterinary Medicine, says, "Due to inherent variability’s in the dog population, there never will be a magic test or a set feeding equation that works for every dog. Owners need to repeatedly evaluate a dog's body condition." Ralston Purina Research Fellow Dorothy Laflamme, D.V.M., Ph.D., a veterinary nutrition specialist, says, "Ideal body condition should be the goal. It is the best way to determine a dog's energy needs. You should be able to feel a dog's ribs without excess fat, and when you took down at a dog, its waist should be apparent behind the ribs. The amount of food fed may need adjustment to obtain and maintain ideal body condition-" The variables that impact a dog's energy requirement - age metabolism, reproductive status, activity and environment - can frequently change. A dog being trained and conditioned for a trial season is likely to be very active and have a high-energy requirement, but as the dog transitions to the noncompetitive season, its high-energy needs taper off. "The energy needs of dogs change along with changes in activity, temperature and other factors," says Tony Buffington, D.V.M., Ph.D., professor of clinical nutrition at Ohio State University College Of Veterinary Medicine. "The number of factors involved in determining an individual dog's energy needs make it impossible for anyone to adequately predict the quantity of food to feed 80 million individual dogs.” Diet and
Energy A dog requires a constant source of energy to fuel its body. Energy from food supports physical work and activity and is used to regulate body temperature and to maintain and synthesize body tissues. These functions make energy the most critical part of a dog's diet - other than water. Carbohydrate, fat and protein are the three nutrients that contribute energy. Fat is more energy dense than protein or carbohydrate and supplies an average of 8.5 kilocalories of metabolizable energy per gram. In comparison, protein and carbohydrate supply an average of 3.5 kilocalories of metabolizable energy per gram. Metabolizable energy is energy ultimately available to a dog after fecal and urine losses. Energy density, also called caloric density, is a measure of chemical energy in food that is transformed by the body into heat. It determines how much food a dog requires each day and directly affects the amount of all other essential nutrients a dog receives (see "Assessing Dietary Nutrient-to-Energy Ratios" on page II). As a food's energy density increases, the required volume of food decreases. "It is important to select a complete and balanced food with an appropriate energy density to match the energy level of the dog," Laflamme says. "For example, if you fed a high-energy performance dog a low-energy food, it would require feeding large portions, perhaps exceeding its stomach capacity or at least forcing it to be greatly distended with each meal. If you fed a low-energy dog a food high in energy, it would require feeding a very small volume, which could leave the dog feeling hungry." Energy
Maintenance Energy maintenance - the key to attaining energy balance and ideal body condition - occurs when there is neither a net gain nor loss of energy from the body. "Maintenance is the state in which most dogs live for the majority of their lifetime," says Purina Nutrition Scientist Arleigh Reynolds, D.V.M., Ph.D. "Energy for maintenance is used for regulating body temperature, routine activity and metabolic processes." A dog's energy requirements change as it goes through various life stages. A growing puppy needs two to three times the energy of an adult dog, and a lactating bitch may need three times its normal energy requirement. "When a dog is going through a production process, such as pregnancy or growth, maintenance is the metabolic overhead that must be paid before the production process can occur," Reynolds says. "The first priority of ingested energy is to support maintenance body function. Energy intake above maintenance requirements is then used to support production processes. Nutrient flow is directed by changes in hormone secretions. In this way, tissues with the highest requirement get the highest priority as nutrients are distributed." Metabolic
Body Weight Energy requirements for dogs vary in part because of a wide fluctuation in body size and weight. Adult dogs of different breeds can vary in weight from just a few pounds to more than 200 pounds. The amount of energy a dog uses relates to its total body surface area, rather than weight, so the relationship between weight and energy requirement is best expressed in terms of total surface area, called metabolic body weight. In addition, energy needs are influenced by the proportion of lean or fat contributing to total body weight. "Not all tissue is equally metabolically active," Michel says. "Body fat is not an energy-consuming tissue. It contributes little to energy consumption, especially in contrast to lean body mass. A young dog with a relatively high proportion of lean tissue will have a higher basal metabolic rate and a greater energy need than an elderly neutered dog of the same weight with a greater proportion of body fat." Estimating
Energy Requirements Through the years, a number of equations have been devised to estimate the maintenance energy requirement of dogs. In 1985, for example, the National Research Council Subcommittee on Dog Nutrition published formulas based on a study of 55 dogs representing seven breeds, with body mass ranging front 4 kilograms to 36 kilograms. "Determining a dog's energy requirement using air equation is fraught with uncertainty," Michel says. "The inability of calculations to account for variations among breeds contributes to a plus or minus margin of error of 25 percent. For some equations, the margin of error is even beyond 25 percent." Energy
Imbalance Energy imbalance occurs when a dog overeats or is underfed, leading to changes in its growth rate, body weight and body composition. Extremes of body condition can present health risks regardless of a dog's age or breed. Overeating, or excess energy intake, occurs more frequently than an energy deficiency and represents the most common form of malnutrition. During growth, overconsumption of energy can have several detrimental effects, especially for large and giant breeds. Feeding growing puppies an excess amount of a high-energy food to attain maximal growth can contribute to skeletal disorders such as osteochondrosis and hip dysplasia. Energy deficiency results in a generalized loss of body weight. Inadequate energy intake may result in hypoglycemia in small-breed puppies and reduced growth rate and compromised development in young dogs. A young dog is extremely sensitive to energy deficiency; in fact, its growth could be slowed or completely stopped. In an adult dog, lactation or performance could be impaired. Body
Condition Scoring "Determining energy needs for an individual dog lies in the hands of the owner," Michel says. "Veterinarians often see a dog only one time a year at a wellness examination, and a lot can happen in a year. A dog can begin getting heavy and need to have its food reduced. Owners have to know how to score their dog to determine body condition," The key message for dog owners is to balance the energy density of food to the energy needs of an individual dog. "Assuming the food provides complete and balanced nutrition and it meets the nutritional needs of the dog, an owner should start by following the feeding guidelines," Laflamme says. "Owners must remember that feeding guidelines are just that - guidelines - and they must make adjustments based on the response in their dog." Ralston Purina Company. Used with permission from
Today’s Breeder. Issue 34
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