Sheep & Goats

Are we breeding more efficient sheep? The role of maternal genetics in feed intake and methane emissions

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Abstract

Genetic indexes are widely used across sheep-producing countries to improve animal productivity and profitability. The sheep industry faces increasing pressure to improve sustainability without compromising productivity. Therefore, it is essential to assess how current maternal breeding objectives align with long-term sustainability goals. This study aimed to evaluate how ewes differing in maternal genetic group, based on current breeding indexes, perform for key efficiency and environmental traits including dry matter intake (DMI) and methane (CH4) emissions, which are not included in current breeding indexes. A total 200 ewes per production cycle representing four contrasting maternal genetic groups (comprising of purebred Suffolk and Texel ewes), including elite New Zealand (NZ), elite Irish (Elite Irish), a cross between elite NZ and elite Irish (NZà—Elite Irish), and low Irish (Low Irish) were evaluated across four production cycles. Ewes were assigned using Irish breeding index, with elite Irish and NZ ewes in the top 20% and low Irish in the bottom 20%. Methane emissions (CHâ‚„ g/day) were estimated annually for all ewes using portable accumulation chambers. Dry matter intake was measured using the n-alkane technique on a subset of ewes across three annual measurement points yielding 474 DMI records across the experiment. Further phenotypic data enabled the evaluation of traits including: DMI and methane expressed per kg live-weight (LW), methane yield (g CH4/kg DMI); ewe production efficiency was calculated as the ratio of weaned litter weight to ewe pre-mating LW (kg weaned litter/kg ewe LW). Statistical analyses were carried out using a linear mixed model; ewe genetic group, ewe parity, ewe birth and rearing type, days since lambing, and date of measurement included as fixed effects, with ewe included as a repeated effect and sire of the ewe included as a random effect. When CHâ‚„ variables were the dependent variables, chamber and lot number by date of measurement were included as fixed effects. Dry matter intake differed with genetic group (P4/day (Elite Irish) to 25.94 g CH4/day (NZ). A similar trend was observed when CH4 was expressed per kg LW (P4 yields were associated with NZ ewes (13.36 g CH4 /kg DMI) compared to all other genetic groups (P< 0.05). Elite and Low Irish ewes weaned the smallest proportion of LW compared to NZ and NZ*Elite Irish(P< 0.001). Overall, the results indicate capacity for improved efficiency and productivity, although a trade-off between productivity and environmental gains may be required.

Keywords: 2026

How to Cite:

Biggins, A., McGovern, F., O’ Connor, E., Boland, T., Walsh, H. & McHugh, N., (2026) “Are we breeding more efficient sheep? The role of maternal genetics in feed intake and methane emissions”, World Congress on Genetics Applied to Livestock Production Digital Archive 2026(1): 2285609. doi: https://doi.org/10.31274/wcgalp.23751

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