I T HAS become increasingly clear in recent years that the formulation of modern poultry diets requires the use of energy values of feedstuffs in one form or another. In 1946, Fraps published in terms of productive energy the caloric value of many feedstuffs. More recently Hill and Anderson (1955) and Titus (1955) revised the energy values given by Fraps and suggested the use of metabolizable energy values instead of productive energy values claiming that metabolizable energy values are more easily obtained and are less subject to variation. Brody (1945) stated that the metabolizable energy value of a feed ingredient is not decreased by a nutrient deficiency while productive energy is. Because of this he stated that the specific dynamic action of a deficient diet must be greater than that of a complete diet. Mitchell and Carman (1926) reported that a deficiency of sodium and chlorine in a diet limited the utilization of the energy and protein of the diet for growth. They also found in rats and chicks that such a deficiency did not lower the metabolizable energy of the diet. They concluded that the increased utilization of energy observed when NaCl was added to the diet deficient in sodium and chlorine was due to a decrease in "specific dynamic effect." Kleiber, Goss and Guilbert (1936) made similar observations while studying phosphorus deficiency and food utilization in cattle. Swift el al. (1934) demonstrated that heat loss was increased in rats on a cystine deficient diet.The experiments presented in this paper were designed to study the energy metabolism of the chick on a methionine deficient diet and on the same diet supplemented with methionine. Special attention is given to the comparison between productive energy and metabolizable energy values of the diets.
EXPERIMENTALIn the first part of this work use was made of birds in two experiments in which a study of a diet severely deficient in methionine was being made. The diet used is that one described by Baldini and Rosenberg (1955) as diet 6. In the first experiment, data were taken at the end of the seventh week and the eighth week. At each of these times, the total feed eaten and total feces excreted during a 24hour period were measured for selected duplicate groups. The feed and feces were sampled and frozen for later use. At the end of the eighth week, three average size birds from each group (six per treatment) were collected and prepared for analysis as described by Baldini and Rosenberg (1957). In the second experiment, the same procedure was followed except that it was done only at the end of the eighth week.The feces and chicken samples were dried in a vacuum oven to determine moisture content and then the caloric value of all samples, feces, chicken, and feed were determined in a Parr adiabatic oxygen bomb calorimeter by the standard method. This procedure made it pos-1177 at University of
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