An Open-Circuit Indirect Calorimetry Head Hood System for Measuring Methane Emission and Energy Metabolism in Small Ruminants

Abstract

Methane (CH4) is a natural by-product of microbial fermentation in the rumen and is a powerful greenhouse gas. An open-circuit indirect calorimetry system for continuous determination of CH4 and CO2 production and O2 consumption and, thereafter, heat production (HP) calculation for small ruminants was described and validated. The system consisted of a computerized control, data acquisition and recording system for gases and air flux. The average value ± standard deviation for the calibration factors in the system were 1.005 ± 0.0007 (n = 6), 1.013 ± 0.0012 (n = 6) and 0.988 ± 0.0035 (n = 6) for O2, CO2 and CH4, respectively. Calibration factors close to 1 confirmed the absence of leaks in the indirect calorimetry system. In addition, an experimental test with 8 goats at mid lactation was conducted to validate the system. The repeatability for CH4 and heat production measured with the open-circuit indirect calorimetry system was 79% and 61%, respectively. Daily average HP measured by indirect calorimetry (Respiration Quotient method) was close to the average HP determined from Carbon-Nitrogen balance (CN method), accounting for 685 and 667 kJ per kg metabolic body weight, respectively. Therefore, discrepancies averaged 1.92%, a rather satisfactory value considering the substantial amount of technical and analytical work involved. The close agreement found between both methods can be considered as being indicative of the absence of systematic error. Two diets with different forage were tested: 40% was either alfalfa hay (HAY) or alfalfa silage (SIL), and the proportion of concentrate was the same in both groups (60%). The experimental trial shown that HP and CH4 were higher in HAY than SIL diet (differences between treatments of 28 kJ of HP per kg of metabolic body weight and 7.1 L CH4/day were found). The data acquisition and recording device developed improved the accuracy of the indirect calorimetry system by reducing the work involved in managing output data and refining the functionality for measuring gas exchange and energy metabolism in small ruminants.

Inclusion of lemon leaves and rice straw into compound feed and its effect on nutrient balance, milk yield, and methane emissions in dairy goats

“…Although the unit was an autocalibrated model, the analyzers were calibrated with reference gases before each test. Fernández et al (2012Fernández et al ( , 2015Fernández et al ( , 2019a described the mobile open-circuit respirometry system used for these measurements. The whole system was calibrated by injecting pure N 2 and CO 2 into the head box (McLean and Tobin, 1987), determined gravimetrically using a precision scale (MOBBA mini-SP 0.2-30 kg, Industrial Weighing System, Barcelona, Spain).…”

Alterations in Energy Partitioning and Methane Emissions in Murciano-Granadina Goats Fed Orange Leaves and Rice Straw as a Replacement for Beet Pulp and Barley Straw

“…Gas analyzer measured O 2 following paramagnetic principle, and CH 4 and CO 2 were measured following the infrared principle (Easyflow Gas Analyzer, model 3020, ABB, Alzenau, Germany). Reference gases were used to calibrate the gas analyzers before each test, and for a deep and detailed explanation of the portable open-circuit respirometry system used in this study it is advisable to consult the following works: Fernández et al [ 17 , 18 , 19 ]. Further, the entire system was gravimetrically calibrated by injecting pure gas N 2 and CO 2 into the head-hood [ 20 ] (precision scale MOBBA mini-SP 0.2–30 kg, Industrial Weighing System, Barcelona, Spain).…”

Towards Sustainable Livestock Production: Estimation of Methane Emissions and Dietary Interventions for Mitigation

“…Further, the head hood, made up of clear polycarbonate material, allows a full range of vision to the animal during the sampling time [59]. The sufficiently large headbox allows the animal to move its head effortlessly to access feed and water and to lay down [11,60]. The ventilated hood systems can be used consecutively over 24 h or for longer periods to measure CH 4 emission.…”

“…The ventilated hood systems can be used consecutively over 24 h or for longer periods to measure CH 4 emission. This can be useful for researchers trying to establish a link between CH 4 emission, feed consumption, and energy metabolism [60]. In addition to the CH 4 measurement, this equipment can measure ethanol, methanol, water vapor, nitrous oxide, acetic acid, CO 2 , and oxygen (O 2 ) from the animal on a real-time basis [61].…”