Page 60 - Small Animal Clinical Nutrition 5th Edition

60 Small Animal Clinical Nutrition

Table 5-1. Commonly used measurements of energy. lactation or growth. DER equals RER plus energy needed for
physical activity and production. DER will be used through-
VetBooks.ir Basal energy requirement (BER): BER represents the energy out this text because it offers a practical and immediately
requirement for a normal animal in a thermoneutral environ-
ment, awake but resting and in postabsorptive (fasting) state.
Other names: fasting heat production (FHP), basal metabolic usable energy requirement value for veterinarians and their
health care teams. Table 5-2 summarizes energy requirements
rate (BMR), basal energy expenditure (BEE).
Resting energy requirement (RER): RER represents the for cats and dogs.
energy requirement for a normal but fed animal at rest in a ther-
moneutral environment. RER differs from BER in that it includes Daily Energy Requirements
energy expended for recovery from physical activity and feed-
ing. Therefore, the difference between BER and RER includes Measuring the energy expenditure of an individual animal is
energy needed for digestion, absorption and metabolism of impractical for practicing veterinarians and pet owners.
food (heat increment) and recovery from previous physical Therefore, researchers have developed prediction equations
activity. Other names: resting energy expenditure (REE).
Maintenance energy requirement (MER): MER represents that may be used to estimate DER. Most of the equations pre-
the energy requirement of a moderately active adult animal in a dict RER based on the easily measured parameter of body
thermoneutral environment. It includes energy needed for weight. After the RER is estimated, one can calculate DER by
obtaining, digesting and absorbing food in amounts to maintain
body weight, as well as energy for spontaneous activity. MER multiplying RER by an appropriate factor.The DER for grow-
does not include energy needed to support additional activity ing, pregnant, lactating and exercising animals includes energy
(work, gestation, lactation and growth). Other names: mainte- needed for maintenance plus the additional energy for work
nance energy expenditure (MEE).
Daily energy requirement (DER): DER represents the average and production, thus different multiplication factors are used
daily energy expenditure of any animal, dependent on lifestage for each situation (Table 5-2). Similarly, deviations from the
and activity. DER differs from MER in that it includes activity RER due to breed, gender, neuter status, presence of disease
necessary for work, gestation, lactation and growth, as well as
energy needed to maintain normal body temperature. and environmental conditions can be included in the multipli-
Heat production (HP): HP is the sum of heat loss through cation factor to improve the accuracy of predicting the DER for
radiation, convection, conduction and evaporation and heat an individual animal. In routine veterinary practice, these ener-
stored in the body as exemplified by an increase in body tem-
perature. Heat is lost when food is metabolized (heat incre- gy requirement equations should be used as guidelines, starting
ment) and when physical work is performed. points or estimates of energy requirements for individual ani-
Heat increment (HI): HI is heat produced from the digestion, mals and not as absolute requirements.
absorption and metabolism of food. Other names: specific
dynamic action (SDA), thermic effect of food, diet-induced ther-
mogenesis. SIZE
Gross energy (GE): GE is the total heat produced by burning a It was known as early as the eighteenth century that large
food in a bomb calorimeter.
Digestible energy (DE): DE is the energy remaining after the animals produced more heat than small animals. Research in
energy lost from feces is subtracted from GE. the nineteenth century, however, showed that small animals
Metabolizable energy (ME): ME is energy available to the ani- produced more heat per unit of body weight (body surface area)
mal after energy from feces, urine and combustible gases has
been subtracted. than large animals (Blaxter, 1989; Kleiber, 1961; Schmidt-
Kilocalorie (kcal): One calorie is the energy needed to raise Neilsen, 1984). Body surface area became the standard means
the temperature of 1 g of water from 14.5 to 15.5°C. 1 kcal = of expressing energy metabolism within a species and makes
1,000 calories = 4.184 kJ.
Kilojoule (kJ): One kilojoule equals 107 ergs, or the energy sense because rate of heat loss from a body to the environment
expended when 1 kg is moved 1 m by 1 newton. 1 kJ = 0.239 is proportional to the area of its surface.
kcal. Although use of body surface area makes sense, it is not eas-
ily determined in animals. Equations to predict body surface
0.67
energy needed for: 1) digestion, absorption and metabolism of area from body weight were developed (BW ) ; however,
kg
food (heat increment) and 2) recovery from previous physical because of different body shapes, calculated surface area did
activity. An animal in a maintenance state has no net change in not vary with body weight to the 0.67 power in some animals
body composition; it produces no products and does not per- (e.g., compare a Labrador retriever weighing 30 kg with an
form work. Irish setter of the same weight, or a French bulldog with a
Maintenance energy requirement (MER) is the energy whippet) (Blaxter, 1989). In the early 1930s, Kleiber and
required to keep an animal in a maintenance state. MER Brody ignored the concept of body surface area and through
includes energy needed for: 1) basal metabolism, 2) obtaining, numerous animal experiments showed that energy require-
digesting and absorbing food in amounts to maintain body ments for a variety of different species are more closely repre-
composition and 3) spontaneous voluntary activity (standing sented as metabolic rate (kcal/day) = 73.3(BW ) 0.74 or
kg
up, lying down, moving about to eat, drink and void feces and 70.5(BW kg ) 0.734 . In an effort to simplify calculations,
urine). MER does not include energy needed to support addi- researchers have proposed and used modifications of Kleiber-
tional physical activity (e.g., exercise or work) and production Brody equations using different exponents or converting
(e.g., gestation, lactation, growth). exponential formulas to linear formulas (Kronfeld, 1991; Hill,
DER represents the average daily energy requirement of any 1993; Burger and Johnson, 1991; Earle and Smith, 1991;
animal. DER depends on lifestage and activity. It differs from Allen and Hand, 1990).
MER in that it includes activity necessary for work, gestation, The debate about whether to use an exponential equation