Ranking cows’ methane emissions under commercial conditions with sniffers versus respiration chambers

This study assessed the ranking of dairy cows using individual-level correlations for methane (CH₄) emission on-farm using sniffers and in respiration chambers. In total 20 lactating dairy cows, ten Holstein and ten Jerseys were recorded using sniffers installed in milking robots for three weeks of lactation and subsequently in respiration chambers (RC) where they were each recorded on three occasions within the RC. Bivariate linear mixed models were used to determine the individual-level correlations (r_I) between sniffer and RC phenotypes as proxies for genetic correlations. Despite differences in feeding and management, the predicted CH₄ production from sniffers correlated highly with RC CH₄ production r_I = 0.77 ± 0.18 and CH₄ breath concentration correlated nearly as well with RC CH₄ production r_I = 0.75 ± 0.20. These correlations between sniffers on-farm and RC demonstrate the potential of sniffers measurements as large-scale indicator traits for CH₄ emissions in dairy cattle.

本研究利用农场环境下安装的嗅探器（sniffer）以及呼吸舱（respiration chambers, RC）中测得的个体水平甲烷（CH₄）排放相关性，对泌乳奶牛的甲烷排放排名进行评估。本研究共纳入20头泌乳奶牛，包含10头荷斯坦奶牛与10头娟姗奶牛：研究人员先借助安装于挤奶机器人中的嗅探器，对其开展为期三周的泌乳期数据采集，随后将每头奶牛安置于呼吸舱中，分别完成三次数据记录。本研究采用双变量线性混合模型，以嗅探器与呼吸舱表型值之间的个体水平相关系数（r_I）作为遗传相关性的替代指标，计算二者的个体水平相关性。尽管饲喂模式与饲养管理存在差异，但嗅探器测得的甲烷产气量预测值与呼吸舱测得的甲烷产气量呈现高度相关，个体水平相关系数r_I=0.77±0.18；嗅探器测得的呼吸甲烷浓度与呼吸舱甲烷产气量的相关性亦较为接近，个体水平相关系数r_I=0.75±0.20。上述农场嗅探器与呼吸舱的相关性结果证实，嗅探器测量数据可作为乳用奶牛甲烷排放的规模化指示性状，具备良好的应用潜力。