GENETIC INFLUENCE ON ENERGY-REQUIREMENTS .3. MULTIFACTORIAL INHERITANCE MODULATED BY GENDER

A conversion index (CI) which measures the efficiency of utilization o f dietary energy was found to be normally distributed in Wistar rats. The Ci used was a ratio of the amount of food ingested to achieve an i ncrement of one gram of body weight during the period of 32 days start ing on day 21 after weaning. We had previously reported that male rats are more efficient energy converters than females. As a way to explor e the hypothesis that the inheritance of the regulation of energy requ irements is multifactorial, we mated Fl rats with high CI (poor energy converters) and studied the CI of their F2 offspring. The males behav ed in agreement with the hypothesis as the F2 males had higher CI than the F1 males, but the behavior in females was different, i.e. the F2 were better converters than the F1. We have no explanation for this ge nder discrepancy.