Aubry Aurélie, Yan Tianhai
Agri-Food and Biosciences Institute, Hillsborough, Co. Down BT26 6DR, UK.
Anim Nutr. 2015 Sep;1(3):128-134. doi: 10.1016/j.aninu.2015.08.015. Epub 2015 Sep 2.
Recent developments suggest the use of other gases such as carbon dioxide (CO) to estimate methane (CH) emissions from livestock, yet little information is available on the relationship between these two gases for a wide range of animals. A large respiration calorimeter dataset with dairy cattle ( = 987 from 30 experiments) was used to investigate relationships between CH and CO production and oxygen (O) consumption and to assess whether the predictive power of these relationships could be improved by taking into account some dietary variables, including forage proportion, fibre and metabolisable energy concentrations. The animals were of various physiological states (young = 60, dry cows = 116 and lactating cows = 811) and breeds (Holstein-Friesian cows = 876, Jersey × Holstein-Friesian = 47, Norwegian = 50 and Norwegian × Holstein-Friesian = 14). The animals were offered forage as a sole diet or a mixture of forage and concentrate (forage proportion ranging from 10 to 100%, dry matter basis). Data were analysed using a series of mixed models. There was a strong positive linear relationship between CH and CO, and observations within an experiment were very predictable (adjusted = 0.93). There was no effect of breed on the relationship between CH and CO. Using O instead of CO to predict CH production also provided a very good fit to the observed empirical data, but the relationship was weaker (adjusted = 0.86). The inclusion of dietary variables to the observed CO emissions, in particular forage proportion and fibre concentration, provided a marginal improvement to the prediction of CH. The observed variability in the CH:CO ratio could only marginally be explained by animal physiological state (lactating vs. dry cows and young cattle) and dietary variables, and thus most likely reflected individual animal differences. The CH:CO ratio can therefore be particularly useful to identify low CH producing cows. These findings indicate that CO production data can be used to accurately predict CH emissions to generate large scale data for management and genetic evaluations for the dairy industry.
近期的研究进展表明，可以使用二氧化碳（CO）等其他气体来估算家畜的甲烷（CH）排放量，但关于这两种气体在多种动物中的关系，目前可用信息较少。利用一个包含奶牛的大型呼吸量热计数据集（来自30项实验，共987头）来研究CH与CO产生量以及氧气（O）消耗量之间的关系，并评估考虑一些饮食变量（包括草料比例、纤维和可代谢能量浓度）是否能提高这些关系的预测能力。这些动物处于不同的生理状态（幼牛60头、干奶牛116头和泌乳奶牛811头）和品种（荷斯坦 - 弗里生奶牛876头、泽西×荷斯坦 - 弗里生47头、挪威牛50头和挪威×荷斯坦 - 弗里生14头）。给动物提供的饲料为单一草料或草料与精饲料的混合物（草料比例以干物质计，范围从10%到100%）。使用一系列混合模型对数据进行分析。CH与CO之间存在很强的正线性关系，且实验中的观测值具有很高的可预测性（调整后 = 0.93）。品种对CH与CO之间的关系没有影响。用O代替CO来预测CH产生量也能很好地拟合观测到的经验数据，但关系较弱（调整后 = 0.86）。将饮食变量纳入观测到的CO排放量中，特别是草料比例和纤维浓度，对CH的预测有一定程度的改善。观测到的CH:CO比值的变异性只能部分地由动物生理状态（泌乳奶牛与干奶牛和幼牛）和饮食变量来解释，因此很可能反映了个体动物差异。因此，CH:CO比值对于识别低CH排放奶牛可能特别有用。这些发现表明，CO产生量数据可用于准确预测CH排放量，从而为乳制品行业的管理和遗传评估生成大规模数据。
