Linear and non-linear estimates of the efficiency with which metabolizable energy is used for maintenance or gain

Linear estimates of the efficiency of metabolizable energy (ME) for maintenance (km) or gain (kg), calculated by Lofgreen and Garrett (1968), the basis for the California Net Energy System (CNES), differ from estimates calculated from metabolic pathways; observations in the former are consistent with the statement that km is greater than kg and the converse for the latter. In their analysis these authors describe metabolizable energy intake as both response and predictor variable. A further assumption is that the relationship between retained energy (RE) and ME intake is rectilinear; this assumption is based on a static maintenance requirement. An analysis by Blaxter (1956) and others, showed that maintenance is dynamic. This study was undertaken to evaluate equations representing either linear or nonlinear relationships between ME intake and (RE) to compare estimates of km and kg