Conversion Efficiencies in Heterotrophic Organisms

Summary 1. The maximum possible efficiency at which living systems are able to convert input nutrients to their own biomass is between 70 and 80 %. 2. Conversion efficiency in bacteria, protozoa and metazoan cells in culture approximates more closely to 60%. 3. Conversion efficiency during embryonic development begins below 60% and rises above this level in the later stages. 4. Very young, post‐natal organisms have high net efficiencies; 50 to 70% in homeotherms and 50 to 80 % in poikilotherms. 5. In cellular systems, capable of proliferation, conversion efficiency is independent of food supply. This means that conversion is directly dependent on nutrient supply. 6. Control of growth at the tissue level may occur through the control of the supply of nutrients to the tissues and its entry into the cells. 7. Compensatory growth, after and during undernutrition, involves increased absorption efficiency and reduced metabolic costs.