There is considerable interest in improving feed utilization of dairy cattle while limiting losses to the environment (i.e., greenhouse gases, GHG). To breed for feed-efficient or climate-friendly cattle, it is first necessary to obtain accurate estimates of genetic parameters and correlations of feed intake, greenhouse gases, and production traits. Reducing dry matter take (DMI) requirements while maintaining production has high economic value to farmers, but DMI is costly to record and thus limited to small research or nucleus herds. Conversely, enteric methane (CH4) currently has no economic value, is also costly to record, and is limited to small experimental trials. However, breath gas concentrations of methane (CH4c) and carbon dioxide (CO2c) are relatively cheap to measure at high throughput under commercial conditions by installing sniffers in automated milking stations. The objective of this study was to assess the genetic correlations between DMI, body weight (BW), fat- and protein-corrected milk yield (FPCM), and GHG-related traits: CH4c and CO2c from Denmark (DNK) and the Netherlands (NLD). A second objective was to assess the genetic potential for improving feed efficiency and the added benefits of using CH4c and CO2c as indicators. Feed intake data were available on 703 primiparous cows in DNK and 524 in NLD; CH4c and CO2c records were available on 434 primiparous cows in DNK and 656 in NLD. The GHG-related traits were heritable (e.g., CH4c h2: DNK = 0.26, NLD = 0.15) but were differentially genetically correlated with DMI and feed efficiency in both magnitude and sign, depending on the population and the definition of feed efficiency. Across feed efficiency traits and DMI, having bulls with 100 daughters with FPCM, BW, and GHG traits resulted in sufficiently high accuracy to almost negate the need for DMI records. Despite differences in genetic correlation structure, the relatively cheap GHG-related traits showed considerable potential for improving the accuracy of breeding values of highly valuable feed intake and feed efficiency traits.

中文翻译：

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呼吸中的温室气体可以用于遗传改良奶牛的饲料效率吗？

在改善奶牛饲料利用率同时限制对环境的损失（即温室气体，温室气体）方面，存在着很大的兴趣。为了育成饲料效率高或对气候友好的牛，首先必须获得遗传参数的准确估计值以及饲料摄入量，温室气体和生产特性的相关性。在保持生产的同时减少干物质摄入量（DMI）的要求对农民具有很高的经济价值，但是DMI记录成本很高，因此仅限于小型研究或有核畜群。相反，肠甲烷（CH4）目前没有经济价值，记录费用也很高，并且仅限于小型实验试验。然而，通过在自动挤奶站中安装吸气器，在商业条件下以高通量测量时，甲烷（CH4c）和二氧化碳（CO2c）的呼吸气体浓度相对便宜。这项研究的目的是评估DMI，体重（BW），脂肪和蛋白质校正的牛奶产量（FPCM）以及与温室气体相关的性状之间的遗传相关性：丹麦（DNK）和荷兰的CH4c和CO2c（ NLD）。第二个目标是评估提高饲料效率的遗传潜力以及使用CH4c和CO2c作为指标的额外好处。DNK和NLD的524头初乳母牛的饲料摄入量数据可用；CH4c和CO2c记录可在DNK的434头初乳牛和NLD的656头处获得。与温室气体有关的性状是可遗传的（例如，CH4c h2：DNK = 0.26，NLD = 0。15），但在数量和体征上与DMI和饲料效率遗传差异相关，具体取决于种群和饲料效率的定义。在各种饲料效率性状和DMI中，拥有100个具有FPCM，BW和GHG性状的女儿的公牛，其准确性很高，几乎不需要DMI记录。尽管遗传相关结构存在差异，但相对廉价的温室气体相关性状仍显示出极大的潜力，可以提高高价值饲料采食量和饲料效率性状的育种值的准确性。和温室气体特征导致足够高的准确性，几乎可以消除对DMI记录的需求。尽管遗传相关结构存在差异，但相对廉价的温室气体相关性状仍显示出极大的潜力，可以提高高价值饲料采食量和饲料效率性状的育种值的准确性。和温室气体特征导致足够高的准确性，几乎可以消除对DMI记录的需求。尽管遗传相关结构存在差异，但相对廉价的温室气体相关性状仍显示出极大的潜力，可以提高高价值饲料采食量和饲料效率性状的育种值的准确性。