CAS Key Laboratory for Agro-Ecological Processes in Subtropical Region, National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production, South Central Experimental Station of Animal Nutrition and Feed Science in the Ministry of Agriculture, Institute of Subtropical Agriculture, The Chinese Academy of Sciences, Changsha, Hunan 410125, China; College of Animal Science and Technology, Hunan Agricultural University, Changsha 410128, China.
CAS Key Laboratory for Agro-Ecological Processes in Subtropical Region, National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production, South Central Experimental Station of Animal Nutrition and Feed Science in the Ministry of Agriculture, Institute of Subtropical Agriculture, The Chinese Academy of Sciences, Changsha, Hunan 410125, China.
J Dairy Sci. 2019 Jul;102(7):6242-6247. doi: 10.3168/jds.2019-16245. Epub 2019 May 2.
Respiration chambers share one analyzer working in parallel, and methane (CH) concentrations have to be measured at certain intervals. The maximum and minimum values in the kinetics of CH emissions can be missed during the interval between measurements, which may influence the quantification of CH emissions. Chambers must be opened for morning feeding and cleaning, which causes a loss of CH data. Calculation methods are needed to estimate the lost CH emission data, which may influence the estimated amount of daily CH emissions. In this study, we measured the CH emissions of 10 growing Chinese Holstein dairy heifers in respiration chambers. Methane concentrations were measured every 0.5 min to obtain the 23-h kinetics of CH emissions, which were further selected at different intervals between measurements (i.e., 5, 30, 60, 120, 180, and 240 min) to evaluate the effects of interval on quantification of CH emissions. The missing 1-h kinetics of CH emissions before feeding were not measured, and 2 calculation methods were used to estimate the missing 1-h kinetics of CH emissions: mean value of measuring period (the mean method) and the nearest value of measurement just before chamber opening (the nearest method). The results showed that the rates of CH emission from 10 heifers varied from 4.56 to 11.42 g/h. The increment of intervals decreased maximum rate of CH emission and increased minimum rate of CH emission. Interval caused less than 5% of the difference in measuring CH emissions. Although the mean method had greater estimated daily CH emission than the nearest method, the difference was within 3%. The interval between measurements (≤3 h) and calculation method had little influence on enteric CH emission measurements.
呼吸室共用一个并行工作的分析仪，必须每隔一定时间测量一次甲烷（CH）浓度。在两次测量之间的时间间隔内，CH 排放动力学的最大和最小值可能会丢失，这可能会影响 CH 排放的量化。呼吸室必须在早晨打开进行喂食和清洁，这会导致 CH 数据丢失。需要计算方法来估算丢失的 CH 排放数据，这可能会影响每天 CH 排放量的估计值。在这项研究中，我们在呼吸室内测量了 10 头生长中的中国荷斯坦奶牛的 CH 排放量。每隔 0.5 分钟测量一次 CH 浓度，以获得 23 小时的 CH 排放动力学，然后在不同的测量间隔（即 5、30、60、120、180 和 240 分钟）进一步选择，以评估间隔对 CH 排放量化的影响。在喂食前没有测量到 1 小时的 CH 排放动力学，因此使用了 2 种计算方法来估算丢失的 1 小时 CH 排放动力学：测量期间的平均值（平均值法）和在打开呼吸室之前最近的测量值（最近值法）。结果表明，10 头奶牛的 CH 排放率从 4.56 到 11.42 g/h 不等。间隔的增加降低了 CH 排放的最大速率，增加了 CH 排放的最小速率。间隔导致测量 CH 排放的差异小于 5%。虽然平均值法估计的每日 CH 排放量大于最近值法，但差异在 3%以内。测量之间的间隔（≤3 小时）和计算方法对肠道 CH 排放测量的影响很小。
