Sustainability & efficiency

A life cycle assessment for male-skew genetics: Harnessing sex determination as an environmental mitigation strategy in beef-on-dairy production

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Abstract

Male-skew genetics have recently been introduced into beef-on-dairy (BxD) systems to favor steer over heifer production to capture steers' efficiency advantages, but the environmental impact of adopting this approach remains unknown. An ISO-conformant life cycle assessment (LCA) model was used to estimate the environmental footprints of conventional and male-skew genetics within two levels of sire genetic merit in three BxD populations: a marbling and yield-focused system in the United States (US), and a carcass quality-focused system (UK-HQ) and a high growth and yield system in the United Kingdom (UK-HY). Sire genetic merit was determined using proprietary BxD economic selection indices optimized for each population, where sires with indices in the third, middle quintile were assigned average, and sires with indices in the fifth and highest merit quintile, elite. For all populations, the system boundary included the dairy where the BxD calf was conceived, rearer, finisher, and abattoir. Progeny performance phenotypes at the finishing phase (UK-HQ N=10,214, UK-HY N=3,132, and US N=3,185) for days, average daily gain, and dry matter intake were averaged within sire genetic merit level and, for male-skew, sex, to generate LCA inputs. The Product Environmental Footprint 3.1 method was used to quantify 16 impact assessment categories per kilogram of carcass weight. To account for a conservative 90% male skew, a weighted average for each impact category was calculated using 90% of the steer and 10% of the heifer impacts. The climate change impact of male-skew sired animals was 0.23-0.30 kg CO2e/kg carcass weight (1.2-3.8%) lower than conventional sired animals of the same genetic merit, depending on genetic level and population (Table 1). Similar reductions (1.1-4.8%) were observed for particulate matter formation, acidification, and terrestrial eutrophication. Across top impact categories, the impact reduction of switching from conventional to male-skew genetics was either roughly half of (UK-HQ), similar to (UK-HY), or higher (US) than the reduction observed when switching genetic levels from average to elite. The smaller male-skew footprint was driven by the improved growth and feed efficiency of steers compared to heifers over the finishing phase, which in turn decreased the impact from feed production, manure management, and enteric fermentation. These results indicate that use of male-skew genetics at any level of genetic merit is a potent strategy to reduce the environmental footprint of BxD production.

Keywords: 2026

How to Cite:

Cleveland, M. & Lai, E., (2026) “A life cycle assessment for male-skew genetics: Harnessing sex determination as an environmental mitigation strategy in beef-on-dairy production”, World Congress on Genetics Applied to Livestock Production Digital Archive 2026(1): 2286012. doi: https://doi.org/10.31274/wcgalp.23838

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