Ubiquitous parasites drive 33% increase in methane yield from livestock

Of anthropogenic methane emissions 40% can be attributed to agriculture, a majority of which is from enteric fermentation in livestock. With international commitments to tackle drivers of climate change, there is a need to lower global methane emissions from livestock production. Gastrointestinal helminths (parasitic worms) are globally ubiquitous and represent one of the most pervasive challenges to the health and productivity of grazing livestock. These parasites influence a number of factors affecting methane emissions including feed efficiency, nutrient use, and production traits. However their effects on methane emissions are unknown. This is the first study that empirically demonstrates disease-driven increases in methane yield in livestock (grams of CH4 per kg of dry matter intake). We do this by measuring methane emissions (in respiration chambers), dry matter intake (DMI), and production parameters for parasitised and parasite-free lambs. This study shows that parasite infections in lambs can lead to a 33% increase in methane yield (g CH4/kg DMI). This knowledge will facilitate more accurate calculations of the true environmental costs of parasitism in livestock, and reveals the potential benefits of mitigating emission through controlling parasite burdens.

人类活动产生的甲烷排放中，约有40%可归因于农业，其中大部分源自家畜的肠道发酵。在国际社会致力于应对气候变化驱动因素承诺的背景下，降低全球家畜生产过程中的甲烷排放成为必要。胃肠道寄生虫（寄生虫蠕虫）在全球范围内普遍存在，并构成了对放牧家畜健康与生产力的最具普遍性的挑战之一。这些寄生虫影响诸多影响甲烷排放的因素，包括饲料利用率、养分使用和生产性状。然而，其对甲烷排放的影响尚属未知。本项研究首次从实证角度证明了疾病驱动的家畜甲烷产量（每千克干物质摄入的甲烷克数）增加。我们通过测量呼吸室内甲烷排放、干物质摄入量（DMI）以及受寄生虫感染与未感染羊的生产参数来开展此项研究。研究发现，羊的寄生虫感染可能导致甲烷产量增加33%（甲烷克数/千克DMI）。这一认识将有助于更精确地计算寄生虫对家畜真实环境成本的影响，并揭示了通过控制寄生虫负载减轻排放的潜在益处。