International environmental agreements have led to the need to reduce methane emission by dairy cows. Reduction could be achieved through selective breeding. The aim of this study was to quantify the genetic variation of methane emission by Dutch Holstein Friesian cows measured using infrared sensors installed in automatic milking systems (AMS). Measurements of CH₄ and CO₂ on 1508 Dutch Holstein Friesian cows located on 11 commercial dairy farms were available. Phenotypes per AMS visit were the mean of CH₄, mean of CO₂, mean of CH₄ divided by mean of CO₂, and their log₁₀-transformations. The repeatabilities of the log₁₀-transformated methane phenotypes were 0.27 for CH₄, 0.31 for CO₂, and 0.14 for the ratio. The log₁₀-transformated heritabilities of these phenotypes were 0.11 for CH₄, 0.12 for CO₂, and 0.03 for the ratio. These results indicate that measurements taken using infrared sensors in AMS are repeatable and heritable and, thus, could be used for selection for lower CH₄ emission. Furthermore, it is important to account for farm, AMS, day of measurement, time of day, and lactation stage when estimating genetic parameters for methane phenotypes. Selection based on log₁₀-transformated CH₄ instead of the ratio would be expected to give a greater reduction of CH₄ emission by dairy cows.

国际环境协议导致需要减少奶牛的甲烷排放。减少可以通过选择育种来实现。这项研究的目的是量化使用安装在自动挤奶系统（AMS）中的红外传感器测量的荷兰荷斯坦黑白花奶牛甲烷排放的遗传变异。可测量位于11个商业奶牛场的1508头荷兰荷斯坦黑白花奶牛的CH ₄和CO ₂。每次AMS访问的表型为CH _4的平均值，CO _2的平均值，CH ₄的平均值除以CO ₂的平均值以及它们的log ₁₀转化。日志₁₀的可重复性CH ₄转化的甲烷表型为0.27 ，CO ₂为0.31，比率为0.14。这些表型的log ₁₀转化遗传力对于CH ₄为0.11 ，对于CO ₂为0.12 ，对于比率为0.03。这些结果表明，在AMS中使用红外传感器进行的测量是可重复且可遗传的，因此可用于选择较低的CH ₄排放量。此外，在估算甲烷表型的遗传参数时，重要的是要考虑农场，AMS，测量日期，一天中的时间和泌乳阶段。基于log _10转换的CH _4的选择而不是该比率将有望大大降低奶牛的CH ₄排放量。