DIET SELECTION BY JAPANESE-QUAIL (COTURNIX-COTURNIX-JAPONICA) IN RELATION TO AMBIENT-TEMPERATURE AND METABOLIC-RATE

1. A choice between a high-energy, wheat-based, low protein mixture an d a lower-energy, soya-based, high protein mixture was offered to grow ing Japanese quail at ambient temperatures of 20 degrees, 25 degrees, 30 degrees and 35 degrees C. 2. The quail were kept in open-circuit re spiration calorimeters, so that diet selection could be related to ene rgy requirement. 3. Increasing ambient temperature had no significant effect on food intake by weight, but the proportion of the high energy choice decreased and, conversely, the proportion of the lower-energy but higher-protein choice increased. 4. Energy intake was therefore ne gatively correlated with ambient temperature, but protein intake per u nit of energy intake increased, allowing the birds to gain weight at a bout the same rate at all temperatures. 5. Heat production decreased a s ambient temperature increased. Respiratory quotient decreased with i ncreasing temperature, which indicates a reduced utilisation of carboh ydrate as an energy source. 6. Water intake increased with temperature but there were no overt signs of heat stress and there was no signifi cant change in body temperature. 7. Japanese quail selected a dietary mixture which maintained similar growth rates over a wide range of amb ient temperature, by sustaining protein intake but altering energy int ake in line with thermoregulatory energy demands.