Department of Molecular Biology and Genetics, Faculty of Science and Technology, Aarhus University, PO Box 50, DK-8830 Tjele, Denmark.
J Dairy Sci. 2012 Feb;95(2):890-8. doi: 10.3168/jds.2011-4544.
Individual methane (CH(4)) production was recorded repeatedly on 93 dairy cows during milking in an automatic milking system (AMS), with the aim of estimating individual cow differences in CH(4) production. Methane and CO(2) were measured with a portable air sampler and analyzer unit based on Fourier transform infrared (FTIR) detection. The cows were 50 Holsteins and 43 Jerseys from mixed parities and at all stages of lactation (mean=156 d in milk). Breath was captured by the FTIR unit inlet nozzle, which was placed in front of the cow's head in each of the 2 AMS as an admixture to normal barn air. The FTIR unit was running continuously for 3 d in each of 2 AMS units, 1 with Holstein and another with Jersey cows. Air was analyzed every 20 s. From each visit of a cow to the AMS, CH(4) and CO(2) records were summarized into the mean, median, 75, and 90% quantiles. Furthermore, the ratio between CH(4) and CO(2) was used as a derived measure with the idea of using CO(2) in breath as a tracer gas to quantify the production of methane. Methane production records were analyzed with a mixed model, containing cow as random effect. Fixed effects of milk yield and daily intake of the total mixed ration and concentrates were also estimated. The repeatability of the CH(4)-to-CO(2) ratio was 0.39 for Holsteins and 0.34 for Jerseys. Both concentrate intake and total mixed ration intake were positively related to CH(4) production, whereas milk production level was not correlated with CH(4) production. In conclusion, the results from this study suggest that the CH(4)-to-CO(2) ratio measured using the noninvasive method is an asset of the individual cow and may be useful in both management and genetic evaluations.
在自动挤奶系统（AMS）中对 93 头奶牛进行了多次个体甲烷（CH(4)）生产记录，旨在估计 CH(4)生产中个体奶牛的差异。使用基于傅里叶变换红外（FTIR）检测的便携式空气采样器和分析仪单元测量甲烷和二氧化碳。这些奶牛包括 50 头荷斯坦牛和 43 头泽西牛，来自不同胎次和泌乳阶段（平均泌乳天数为 156 天）。FTIR 单元进气口喷嘴捕捉奶牛的呼吸，该喷嘴放置在 AMS 中的每头牛头部前面，作为正常牛舍空气的混合物。FTIR 单元在两个 AMS 单元中每个单元连续运行 3 天，一个单元中是荷斯坦牛，另一个单元中是泽西牛。空气每 20 秒分析一次。从每头奶牛到 AMS 的每次访问中，CH(4)和 CO(2)记录被汇总为平均值、中位数、75%和 90%分位数。此外，CH(4)与 CO(2)的比例被用作衍生指标，其想法是使用呼吸中的 CO(2)作为示踪气体来量化甲烷的产生。使用包含奶牛为随机效应的混合模型分析甲烷生产记录。还估计了牛奶产量和总混合日粮和浓缩物的日摄入量的固定效应。荷斯坦牛的 CH(4)-CO(2) 比值的重复性为 0.39，泽西牛的重复性为 0.34。浓缩物摄入量和总混合日粮摄入量与 CH(4)产量呈正相关，而牛奶产量水平与 CH(4)产量无关。总之，本研究结果表明，使用非侵入性方法测量的 CH(4)-CO(2) 比值是个体奶牛的一个优势，可能在管理和遗传评估中都有用。
