Sheep & Goats

Analysis of methane emissions in UK maternal sheep

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Abstract

Abstract Text: The livestock sector is a major source of anthropogenic Greenhouse Gas (GHG) emissions, primarily releasing methane from enteric fermentation. The objective of this study was to evaluate the efficacy of selective breeding as a scalable strategy for methane mitigation in sheep. To achieve this, we quantified the heritability of methane emission traits and assessed the projected long-term reduction in greenhouse gas output. The successful implementation of a low-emission sheep breeding program necessitates establishing a well-phenotyped animal cohort within a structured genetic improvement scheme to facilitate accurate and effective selection and accelerate the reduction of methane output. This study systematically collected GHG emission data from a large cohort of approximately 10,000 sheep across 28 commercial maternal flocks in the UK, including breeds such as Dorset, Exlana, Lleyn, and composite lines. Methane and carbon dioxide emissions, standardised as g/day, were measured using Portable Accumulation Chambers. Concurrently, health phenotypes (Faecal Egg Counts - FEC and IgA levels) and production phenotypes (body weights taken around 8 and 21 weeks, ultrasound muscle and fat depths) were recorded. All animals were genotyped using a AgR_Ovine_60Kplus_20007095X378523_A1 array. These integrated phenotypic and genomic data were subsequently utilised to estimate variance components and genetic correlations, which will finally allow generation of conventional and genomic Estimated Breeding Values to facilitate direct selection for low-emission animals.Results from this study indicated low to moderate heritabilities for PAC-measured traits, with h2 estimated at 0.04±0.01 for live weight adjusted CH4, 0.22±0.02 for CO2 and 0.25±0.06 for gas ratio (molar proportion of CH4 to the sum of CH4 and CO2 emissions - proxy trait for methane emission relative to feed intake as suggested by Johnson et al., 2022). Heritability for the key production traits was estimated at 0.18±0.04 for 8-week weight, 0.33±0.04 for 21-week weight, 0.29±0.07 for ultrasound muscle depth, and 0.29±0.02) for ultrasound fat depth. Estimated h2 for health traits were 0.38±0.04 for FEC Strongyles, 0.43±0.04 for FEC Nematodirus and 0.39±0.05 for IgA. Critically, all estimated genetic and phenotypic correlations between production and health traits with CO2 and the gas ratio were uniformly very low (≤∣0.1∣) and generally non-significant. Correlations involving CH4 were low to moderate and generally negative, although the associated standard errors suggested that only a few reached statistical significance.This study demonstrates that selective breeding is a viable and scalable strategy for reducing methane emissions in sheep, as the low to moderate heritability of gas traits and their lack of antagonistic genetic correlations with health and production phenotypes allow for significant environmental mitigation without compromising farm productivity.References: Johnson, Hickey, Knowler, Wing, Bryson, Hall, Jonker, Janssen, Dodds, McEwan and Rowe (2022): Genetic parameters for residual feed intake, methane emissions, and body composition in New Zealand maternal sheep. FrontGenet.16;13:911639.

Keywords: 2026

How to Cite:

Kaseja, K., Lambe, N., Dods, E. & Roden, J., (2026) “Analysis of methane emissions in UK maternal sheep”, World Congress on Genetics Applied to Livestock Production Digital Archive 2026(1): 2277968. doi: https://doi.org/10.31274/wcgalp.23428

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