Evaluation of Metabolizable Energy for Poultry

Abstract

ANY authors have reviewed the subject of energy concepts for M poultry nutrition (Titus, 1961;Lockhart et al., 1963;Vohra, 1966;Kurnick, 1967;Kohler and Kuzmicky, 1970). Currently, metabolizable energy values are popular among the consulting nutritionists for use in computer calculations for least cost formulations.No doubt, metabolizable energy (ME) is easier to determine and a more practical measure than net energy or Fraps' productive energy which are measured by the energy stored up as fat and protein in a growing and fattening animal. We are really interested in the efficiency of utilization of metabolizable energy by the animal. In an ideal measure the energy of the diet should equal the sum of the energy values of its constituents. Gross energy is the only such measure but has no practical applicability because not all of this energy is available to the animal. The partition of gross energy (GE) into its various components is outlined in Figure 1.As feces and urine are voided together by poultry, digestible energy (DE) cannot be measured without surgically altering the digestive tract. For the same reason, the determination of digestibility of proteins is equally difficult but has been done by a number of workers (Fraps, 1944;Eckman et al., 1949;Titus, 1957; Rolton, 1957; Kabota and Morimoto, 1965; Vogt and Stute, 1970), who have used any of the following methods for this purpose:(a) Total collection and separation of various urinary constituents. (b) Separate collection of feces and urine by surgically altering the (c) Insert indicator i n the diet and determination of urinary By its very concept, metabolizable energy is "the energy available for anabolism (the building of body substance, milk or eggs) and for katabolimi (the heat production of animals) and requires no correction for nitrogen balance" (Kleiber, 1961). animals. constituents.Thus: ME-GE, = GE, where GE, -Gross energy of the dietary intake GEe -= Gross energy of the equivalent excreta If the metabolizable energy value is corrected for nitrogen balance,The term nitrogen then it should be termed as ME,, (NRC, 1966). 204

Energy and nitrogen metabolism of diseased chickens: Interaction ofAscaridia galliinfestation and vitamin a status

“…ME concentration of the diet was calculated by the difference in food energy intake and excreta energy output. No N correction factor was applied for the reasons suggested by Vohra (1972). Energy balance was calculated for fed chickens as the difference between ME intake and heat production, and for starved chickens as the summation of heat production and energy content of endogenous excreta, collected over the same time interval.…”

Measuring Metabolizable Energy with Mature Hens

“…The procedure employed for correction of apparent ME values for nitrogen retained has been questioned by many researchers (Baldini, 1961;Foster, 1968;Olson, 1970;Vohra, 1972;and Kleiber, 1975). In the present studies no Diets 1 to 4 used in Experiments 1 and 2; 5 and 6 in Experiments 3 and 4; and diets 7 to 9 employed in Experiments 5 and 6.…”

Linear model of nitrogen balance and examination of the nature of true metabolisable energy and its nitrogen corrected form

“…A conceptual appreciation of metabolisable energy may be obtained from partitions of food energy into its utilisable fractions (Vohra, 1972;Farrell, 1974;Sibbald, 1982;Whittlow, 1986). Metabolisable energy (ME c ) is the food energy available to an animal consequent to its metabolic assimilation and includes the associated heat increment.…”