Enteric methane emission can be reliably measured by the GreenFeed monitoring unit
Enteric methane emission can be reliably measured by the GreenFeed monitoring unit
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DOI：
10.1016/j.livsci.2019.01.017
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发表时间：
2019-04-01
影响因子：
1.8
通讯作者：
Hristov, A. N.
中科院分区：
文献类型：
--
作者：
Huhtanen, P.;Ramin, M.;Hristov, A. N.
反刍动物通过向大气中释放甲烷（CH 4）气体而导致全球变暖。这增加了动物科学家开发和改进测量奶牛甲烷产量的方法的兴趣。采用了绿色饲料排放监测装置，通过测量牛进入绿色饲料排放监测装置时的气体浓度和流量来估计甲烷的产量。本研究的目的是比较CH 4生产测量的GEM方程预测CH 4生产。评价的基础上83个治疗手段，从奶牛（n = 65）和生长牛（n = 18）的研究，其中甲烷生产的GEM测量。甲烷产量预测的摄入量和营养成分的数据与18个经验公式主要来自呼吸室（RC）数据集。使用固定和混合回归模型对所有方程的观察值和预测值进行比较。评价是基于均方根预测误差（RMSPE）表示为观察到的平均值的比例。所有方程在高R-2值方面都是精确的（在大多数情况下> 0.90），但在RMSPE方面存在相当大的差异。一般来说，基于CH 4产量和干物质或总能量摄入的方程导致最小的RMSPE。当表示为观察到的平均值的比例时，18个方程的RMSPE为11.2%，范围为6.9%至28.4%。12个方程的RMSPE小于观测平均值的10%。在使用混合模型回归分析估计预测的和测量的CH 4产量之间的关系时，模型的排名仍然相当相似。排除2个具有较大平均偏倚的方程后，从随机研究效应调整的RMSPE平均为观察平均值的6.2%。根MSPE小于方程开发中的相应误差，可能反映了与RC相比，实验室之间GEM系统的标准化校准更多。在直接比较中（n = 20），RC和GEM测量的CH 4产生量之间存在良好的关系（R-2 = 0.92）。根MSPE为35.7 g/d（观测值的12.9%），平均偏倚、斜率偏倚和随机误差分别为MSPE的12%、0%和88%。从目前的分析结果表明，CH 4排放量测量的GEM系统同意以及来自RC数据的经验模型预测值间接表明肠道CH 4排放量可以可靠地测量GEM系统。
Ruminants contribute to global warming by releasing methane (CH4) gas to the atmosphere. This has increased interest among animal scientists to develop and improve methods measuring CH4 production in dairy cows. The GreenFeed emission monitoring unit (GEM) was introduced to estimate CH4 production by measuring gas concentration and flux when cattle visit a GEM. The objective of the present study was to compare CH4 production measured by the GEM with equations predicting CH4 production. Evaluation was based on 83 treatment means from dairy (n = 65) and growing cattle (n = 18) studies, in which CH4 production was measured by GEM. Methane production was predicted from intake and nutrient composition data with 18 empirical equations derived mainly from respiration chamber (RC) datasets. A comparison of observed and predicted values were performed for all equations using fixed and mixed regression models. The evaluation was based on root mean squared prediction error (RMSPE) expressed as a proportion of observed mean. All equations were precise in terms of high R-2 values (in most cases > 0.90), but there were considerable differences in RMSPE. Generally, the equations based on CH4 yield and dry matter or gross energy intake resulted in the smallest RMSPE. When expressed as a proportion of observed mean, RMSPE for the 18 equations was 11.2%, and it ranged from 6.9 to 28.4%. Twelve equations had RMSPE less than 10% of observed mean. Ranking of the models remained rather similar when the relationships between predicted and measured CH4 production was estimated using the mixed model regression analysis. Following the exclusion of 2 equations with large mean bias, RMSPE adjusted from random study effects was on average 6.2% of observed mean. Root MSPE were smaller than the corresponding errors in development of the equations, probably reflecting more standardized calibrations of the GEM system between laboratories compared with RC. In direct comparisons (n = 20) there was a good relationship in CH4 production measured by RC and GEM (R-2 = 0.92). Root MSPE was 35.7 g/d (12.9% of the observed) with mean bias, slope bias and random error being 12, 0 and 88% of MSPE, respectively. Results from the current analysis indicated that CH4 emissions measured by the GEM system agreed well with values predicted by empirical models derived from RC data suggesting indirectly that enteric CH4 emission can be reliably measured by the GEM system.