Accuracy validation of open-circuit respiration chambers for the assessment of energy metabolism and enteric methane emissions in pigs and small ruminants

Respiratory chambers are one of the main methods of obtaining data regarding animal energy metabolism and determine enteric methane emissions from livestock. The boom in research examining methane emissions has led to an increase in the number of facilities where such measurements can be performed. This has concerned various research groups, and emphasis has been placed on implementing a method for validating respiratory chambers according to international standards, thus ensuring that the results are traceable. This study aimed to validate the accuracy of two respiratory chambers for assessing animal energy metabolism and enteric methane emissions from livestock using international standards. The analyzers (oxygen, carbon dioxide, and methane), duct and air extraction system, and chamber were the three components used to validate the complete respiratory chamber system. The linearity and response time of the analyzers, stability of the plateau, and recovery of high-purity gases from the chambers were evaluated for the three components. The average variations in the gas measurements for the supplied reference gas were 1.77 and 1.30 % for the carbon dioxide and methane analyzers, respectively. Recovery test calculations after supplying high-purity carbon dioxide and methane into chambers revealed that the efficiency of gas recovery averages were 1.018 ± 0.0001 and 0.991 ± 0.0001 for chambers one and two, respectively. In conclusion, the respiratory chambers at the National Center of Disciplinary Research in Animal Physiology of INIFAP, Mexico designed for evaluating energy metabolism and enteric methane emissions in livestock, work with accuracy. •Open-circuit respiratory chambers as a method to estimate animal energy metabolism.•Quantification of enteric methane production of ruminants with the use of open-circuit respiratory chambers.•Measurement of greenhouse gases using open-circuit breathing chambers.