Factors Affecting the Metabolizable Energy Content of Poultry Feeds

AKNOWLEDGE of the available energy content of poultry feeds is essential if the most economical rations are to be formulated. The question arises as to which method of describing available energy is to be employed. Practical difficulties, associated with the excretion of both feces and urine via a common cloaca, prevent the derivation of precise digestibility data. Axelsson (1939) and Halnan (1951) have argued strongly against the use of net energy values, and Titus (1955), Davidson et al. (1957) and Hill and Anderson (1958) have found productive energy data to be unsatisfactory. It is, therefore, understandable why many poultry nutritionists have turned to the evaluation of feeds in terms of metabolizable energy (M.E.). It is possible that M.E. values are subject to certain intrinsic errors although there is little published evidence to either support or refute this hypothesis. Matterson et al. (1958) have demonstrated that the M.E. value for a …