There may, however, be instances of management systems that rely on the ability of animals to withstand per- iods of reduced feed quantity or quality and then recover tissue stores through compensatory growth when the diet is more favorable. First, efficiency of using body fat as an energy source is high com- pared 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 environ- ments compared with constant temperature are conflicting. Bond et al. Hahn et al.
Numerous studies suggest that specific climatic variables change total effi- ciency.
Morrison et al. Morrison et al. Measurement of efficiency in the short term can lead to erroneous conclu- sions because of differences in an animal's previous nutritional background. For example, animals that have received restricted intake will compensate with improved feed efficiency when allowed ad libitum intake.