Factors Affecting the Metabolizable Energy Content of Poultry Feeds

THE available energy content of a poultry feed ingredient is not constant but may be influenced by the nature and quantities of the materials with which it is fed. Evidence of this fact was presented by Matterson et al. (1958) who reported that the metabolizable energy (M.E.) content of a sample of corn varied according to whether it was fed alone or in combination with other materials. This finding was reminiscent of that of Mitchell (1942) who reported on the “non-additive” effects of feeds in ruminant nutrition. Wilder et al. (1959) and Kalmbach and Potter (1959) provided evidence that the M.E. values of fats were not constant while Sibbald et al. (1959) demonstrated that dietary protein quality may influence energy availability. Since 1959 a number of reports demonstrating the “non-additivity” of M.E. values have appeared; a few contradictory findings have also been published. Sibbald et al. (1959 (1960a) reported that …