There may, however, be instances of management systems that rely on the ability of animals to withstand periods of reduced feed quantity or quality and then recover tissue stores through compensatory growth when the diet is more favorable. There appear to be two additional reasons for improved efficiency of producing eggs during heat. First, efficiency of using body fat as an energy source is high compared with using energy from feed sources, which results in higher efficiency of egg production during heat exposure. Reports of energetic efficiency for animals exposed to fluctuating environments compared with constant temperature are conflicting. Bond et al.
Numerous studies suggest that specific climatic variables change total efficiency.
Morrison et al. Berry et al. Morrison et al. Further examples of effects of specific climatic variables only substantiate the need to use effective ambient temperature when relating effects of the climatic environment to performance. Measurement of efficiency in the short term can lead to erroneous conclusions because of differences in an animal's previous nutritional background.