An open circuit respirometer for metabolic studies on the domestic fowl: Establishment of standard operating conditions

Synopsis Details of an open circuit respirometer that allows continuous specific measurements of gaseous exchange by the fowl are given. “ Basal” oxygen consumption of the laying hen decreases by 20% during the first 3 d of training to the experimental situation. Thereafter it remains constant. The time required to reach the post‐absorptive state was found to be 24 h for birds weighing less than 2.5 kg and 48 h for those weighing more than 2.5 kg. The mean basal metabolic rate (BMR) of adult laying hens was 11.3 ml O2/kg/4> min and the mean RQ was 0.709.