Assessment of methane emission traits in ewes using a laser methane detector: genetic parameters and impact on lamb weaning performance

• Main Authors: J. Reintke, K. Brügemann, T. Yin, P. Engel, H. Wagner, A. Wehrend, S. König
• Format: Article
• Language: English
• Published: Copernicus Publications 2020-04-01
• Series: Archives Animal Breeding
• Online Access: https://www.arch-anim-breed.net/63/113/2020/aab-63-113-2020.pdf
• ISSN: 0003-9438; 2363-9822

<p>The aim of the present study was to derive individual methane (<span class="inline-formula">CH₄</span>) emissions in ewes separated in <span class="inline-formula">CH₄</span> respiration and eructation traits. The generated longitudinal <span class="inline-formula">CH₄</span> data structure was used to estimate phenotypic and genetic relationships between ewe <span class="inline-formula">CH₄</span> records and energy efficiency indicator traits from same ewes as well as from their lambs (intergenerational perspective). In this regard, we recorded <span class="inline-formula">CH₄</span> emissions via mobile laser methane detector (LMD) technique, body weight (EBW), backfat thickness (BFT) and body condition score (BCS) from 330 ewes (253 Merinoland (ML), 77 Rhön sheep (RH)) and their 629 lambs (478&thinsp;ML, 151&thinsp;RH). The interval between repeated measurements (for ewe traits and lamb body weight (LBW)) was 3 weeks during lactation. For methane concentration (<span class="inline-formula">µ</span>L&thinsp;L<span class="inline-formula">⁻¹</span>) determinations in the exhaled air, we considered short time measurements (3&thinsp;min). Afterwards, <span class="inline-formula">CH₄</span> emissions were portioned into a respiration and eructation fraction, based on a double normal distribution. Data preparation enabled the following <span class="inline-formula">CH₄</span> trait definitions: mean <span class="inline-formula">CH₄</span> concentration during respiration and eructation (<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M11" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msub><mi mathvariant="normal">CH</mi><mrow><msub><mn mathvariant="normal">4</mn><mrow><mi mathvariant="normal">r</mi><mo>+</mo><mi mathvariant="normal">e</mi></mrow></msub></mrow></msub></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="32pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="7e5a12ee149a18e1aaebe69cf940b0b6"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="aab-63-113-2020-ie00001.svg" width="32pt" height="15pt" src="aab-63-113-2020-ie00001.png"/></svg:svg></span></span>), mean <span class="inline-formula">CH₄</span> concentration during respiration (<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M13" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msub><mi mathvariant="normal">CH</mi><mrow><msub><mn mathvariant="normal">4</mn><mi mathvariant="normal">r</mi></msub></mrow></msub></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="24pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="753f3f283e8f6df039cf4ccaef008ccf"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="aab-63-113-2020-ie00002.svg" width="24pt" height="15pt" src="aab-63-113-2020-ie00002.png"/></svg:svg></span></span>), mean <span class="inline-formula">CH₄</span> concentration during eructation (<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M15" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msub><mi mathvariant="normal">CH</mi><mrow><msub><mn mathvariant="normal">4</mn><mi mathvariant="normal">e</mi></msub></mrow></msub></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="26pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="2da985f34e1f7e3b25791577fd70441b"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="aab-63-113-2020-ie00003.svg" width="26pt" height="15pt" src="aab-63-113-2020-ie00003.png"/></svg:svg></span></span>), sum of <span class="inline-formula">CH₄</span> concentrations per minute during respiration (<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M17" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msub><mi mathvariant="normal">CH</mi><mrow><msub><mn mathvariant="normal">4</mn><mi mathvariant="normal">rsum</mi></msub></mrow></msub></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="36pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="db1329923052dfb4850e5f2ef4cd3fbb"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="aab-63-113-2020-ie00004.svg" width="36pt" height="15pt" src="aab-63-113-2020-ie00004.png"/></svg:svg></span></span>), sum of <span class="inline-formula">CH₄</span> concentrations per minute during eructation (<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M19" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msub><mi mathvariant="normal">CH</mi><mrow><msub><mn mathvariant="normal">4</mn><mi mathvariant="normal">esum</mi></msub></mrow></msub></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="37pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="6deaa3ccbe4603ccbcff0bbf299e48c9"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="aab-63-113-2020-ie00005.svg" width="37pt" height="15pt" src="aab-63-113-2020-ie00005.png"/></svg:svg></span></span>), maximal <span class="inline-formula">CH₄</span> concentration during respiration (<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M21" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msub><mi mathvariant="normal">CH</mi><mrow><msub><mn mathvariant="normal">4</mn><mi mathvariant="normal">rmax</mi></msub></mrow></msub></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="36pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="d8879d0d7d848dcd41a237fde098d65e"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="aab-63-113-2020-ie00006.svg" width="36pt" height="15pt" src="aab-63-113-2020-ie00006.png"/></svg:svg></span></span>), maximal <span class="inline-formula">CH₄</span> concentration during eructation (<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M23" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msub><mi mathvariant="normal">CH</mi><mrow><msub><mn mathvariant="normal">4</mn><mi mathvariant="normal">emax</mi></msub></mrow></msub></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="37pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="2fb605304413957c8d939eac43eef2c8"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="aab-63-113-2020-ie00007.svg" width="37pt" height="15pt" src="aab-63-113-2020-ie00007.png"/></svg:svg></span></span>), and eructation events per minute (<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M24" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msub><mi mathvariant="normal">CH</mi><mrow><msub><mn mathvariant="normal">4</mn><mi mathvariant="normal">event</mi></msub></mrow></msub></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="37pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="ff85b25f584cac738fdb8f1b9b1d78f7"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="aab-63-113-2020-ie00008.svg" width="37pt" height="15pt" src="aab-63-113-2020-ie00008.png"/></svg:svg></span></span>). Large levels of ewe <span class="inline-formula">CH₄</span> emissions representing energy losses were significantly associated with lower LBW (<span class="inline-formula"><i>P</i><i>&lt;</i>0.05</span>), lower EBW (<span class="inline-formula"><i>P</i><i>&lt;</i>0.01</span>) and lower BFT (<span class="inline-formula"><i>P</i><i>&lt;</i>0.05</span>). For genetic parameter estimations, we applied single- and multiple-trait animal models. Heritabilities and additive genetic variances for <span class="inline-formula">CH₄</span> traits were small, i.e., heritabilities in the range from &lt;0.01 (<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M30" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msub><mi mathvariant="normal">CH</mi><mrow><msub><mn mathvariant="normal">4</mn><mrow><mi mathvariant="normal">r</mi><mo>+</mo><mi mathvariant="normal">e</mi></mrow></msub></mrow></msub></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="32pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="b9b1a777a8416cf0f1134df9fce09b65"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="aab-63-113-2020-ie00009.svg" width="32pt" height="15pt" src="aab-63-113-2020-ie00009.png"/></svg:svg></span></span>, <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M31" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msub><mi mathvariant="normal">CH</mi><mrow><msub><mn mathvariant="normal">4</mn><mi mathvariant="normal">r</mi></msub></mrow></msub></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="24pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="c22e28542da6336a5adb91f0253a2e2d"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="aab-63-113-2020-ie00010.svg" width="24pt" height="15pt" src="aab-63-113-2020-ie00010.png"/></svg:svg></span></span>, <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M32" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msub><mi mathvariant="normal">CH</mi><mrow><msub><mn mathvariant="normal">4</mn><mi mathvariant="normal">rmax</mi></msub></mrow></msub></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="36pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="b3564b5feb7b175b90260ee6daf4c4f9"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="aab-63-113-2020-ie00011.svg" width="36pt" height="15pt" src="aab-63-113-2020-ie00011.png"/></svg:svg></span></span>, <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M33" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msub><mi mathvariant="normal">CH</mi><mrow><msub><mn mathvariant="normal">4</mn><mi mathvariant="normal">esum</mi></msub></mrow></msub></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="37pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="179b1eb6d661095c1d5615d5e2f64f0b"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="aab-63-113-2020-ie00012.svg" width="37pt" height="15pt" src="aab-63-113-2020-ie00012.png"/></svg:svg></span></span>) to 0.03 (<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M34" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msub><mi mathvariant="normal">CH</mi><mrow><msub><mn mathvariant="normal">4</mn><mi mathvariant="normal">rsum</mi></msub></mrow></msub></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="36pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="7a1cad657c7765763312071de4efb491"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="aab-63-113-2020-ie00013.svg" width="36pt" height="15pt" src="aab-63-113-2020-ie00013.png"/></svg:svg></span></span>). We estimated negative genetic correlations between <span class="inline-formula">CH₄</span> traits and EBW in the range from <span class="inline-formula">−</span>0.44 (<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M37" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msub><mi mathvariant="normal">CH</mi><mrow><msub><mn mathvariant="normal">4</mn><mrow><mi mathvariant="normal">r</mi><mo>+</mo><mi mathvariant="normal">e</mi></mrow></msub></mrow></msub></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="32pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="0783f72e12941c6e5be53cc222ffd3c2"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="aab-63-113-2020-ie00014.svg" width="32pt" height="15pt" src="aab-63-113-2020-ie00014.png"/></svg:svg></span></span>) to <span class="inline-formula">−</span>0.05 (<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M39" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msub><mi mathvariant="normal">CH</mi><mrow><msub><mn mathvariant="normal">4</mn><mi mathvariant="normal">rsum</mi></msub></mrow></msub></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="36pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="85572663a691d6d7bfd1818f90227fce"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="aab-63-113-2020-ie00015.svg" width="36pt" height="15pt" src="aab-63-113-2020-ie00015.png"/></svg:svg></span></span>). Most of the <span class="inline-formula">CH₄</span> traits were genetically negatively correlated with BCS (<span class="inline-formula">−</span>0.81 for <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M42" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msub><mi mathvariant="normal">CH</mi><mrow><msub><mn mathvariant="normal">4</mn><mi mathvariant="normal">esum</mi></msub></mrow></msub></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="37pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="c04da3ec86da415d3b93b4b9f295096a"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="aab-63-113-2020-ie00016.svg" width="37pt" height="15pt" src="aab-63-113-2020-ie00016.png"/></svg:svg></span></span>) and with BFT (<span class="inline-formula">−</span>0.72 for <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M44" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msub><mi mathvariant="normal">CH</mi><mrow><msub><mn mathvariant="normal">4</mn><mi mathvariant="normal">emax</mi></msub></mrow></msub></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="37pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="cb530248d0aef29084680fe871d4f3d1"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="aab-63-113-2020-ie00017.svg" width="37pt" height="15pt" src="aab-63-113-2020-ie00017.png"/></svg:svg></span></span>), indicating same genetic mechanisms for <span class="inline-formula">CH₄</span> output and energy efficiency indicators. Addressing the intergenerational aspect, genetic correlations between <span class="inline-formula">CH₄</span> emissions from ewes and LBW ranged between <span class="inline-formula">−</span>0.35 (<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M48" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msub><mi mathvariant="normal">CH</mi><mrow><msub><mn mathvariant="normal">4</mn><mrow><mi mathvariant="normal">r</mi><mo>+</mo><mi mathvariant="normal">e</mi></mrow></msub></mrow></msub></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="32pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="6dbcd4d5e4c7bb416922d2ac1b7bd867"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="aab-63-113-2020-ie00018.svg" width="32pt" height="15pt" src="aab-63-113-2020-ie00018.png"/></svg:svg></span></span>) and 0.01 (<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M49" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msub><mi mathvariant="normal">CH</mi><mrow><msub><mn mathvariant="normal">4</mn><mi mathvariant="normal">rsum</mi></msub></mrow></msub></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="36pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="51da8a9766cca4d4d160149ff9976495"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="aab-63-113-2020-ie00019.svg" width="36pt" height="15pt" src="aab-63-113-2020-ie00019.png"/></svg:svg></span></span>, <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M50" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msub><mi mathvariant="normal">CH</mi><mrow><msub><mn mathvariant="normal">4</mn><mi mathvariant="normal">rmax</mi></msub></mrow></msub></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="36pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="3d13268f6abc99290d3e993c74754d03"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="aab-63-113-2020-ie00020.svg" width="36pt" height="15pt" src="aab-63-113-2020-ie00020.png"/></svg:svg></span></span>), indicating that breeding on reduced <span class="inline-formula">CH₄</span> emissions (especially eructation traits) contribute to genetic improvements in lamb weaning performance.</p>