Description and function of a mobile open-circuit respirometry system to measure gas exchange in small ruminants

A mobile open-circuit respirometry system was constructed for estimating heat production (HP) in small ruminants from CH4 and CO2 production and O2 consumption by the respiratory quotient (RQ) method. The method was evaluated against HP estimates by C–N balance measurements (CN method). Calibration factors were established injecting N2 into the system. Repetitive and consistent values for the calibration factor were obtained (1.0065 ± 0.01307, n = 9), which confirms the absence of leaks and good performance of the whole system. A pilot experiment with 14 Granadina female dry goats was conducted to evaluate the system. The metabolizable energy intake (MEI) was close to ME for maintenance. Average HP measured by RQ method was in agreement with the average HP determined by CN method accounting for 505 and 500 kJ/kg0.75 BW/d, respectively. It is concluded that the mobile system was suitable for measuring gas exchange and energy metabolism in small ruminants.