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

摘要

&p&The aim of the present study was to derive individual methane (&span class="inline-formula"&CH&sub&4&/sub&&/span&) emissions in ewes separated in &span class="inline-formula"&CH&sub&4&/sub&&/span& respiration and eructation traits. The generated longitudinal &span class="inline-formula"&CH&sub&4&/sub&&/span& data structure was used to estimate phenotypic and genetic relationships between ewe &span class="inline-formula"&CH&sub&4&/sub&&/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"&CH&sub&4&/sub&&/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?Rh?n sheep (RH)) and their 629?lambs (478 ML, 151 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 L&span class="inline-formula"&&sup&?1&/sup&&/span&) determinations in the exhaled air, we considered short time measurements (3 min). Afterwards, &span class="inline-formula"&CH&sub&4&/sub&&/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"&CH&sub&4&/sub&&/span& trait definitions: mean &span class="inline-formula"&CH&sub&4&/sub&&/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"&CH&sub&4&/sub&&/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"&CH&sub&4&/sub&&/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&