PS8-10. Sustainability Assessment of Terminal Beef Production Using Beef × Dairy Straightbred Calves.

Abstract Historically, dairy-derived calves have contributed approximately 20% of the annual U.S. beef supply. Recent adoption of beef genetics in dairy herds has enabled the production of beef × dairy crossbred calves for terminal beef production, potentially improving biological efficiency and environmental outcomes of feedlot systems. However, limited information exists quantifying the sustainability implications of these practices at an industry-wide scale. The objective of this study was to evaluate the greenhouse gas (GHG) emissions intensity of straightbred Holstein versus beef × dairy cross steers during the finishing phase through life cycle assessment (LCA). Growth performance data were collected from peer-reviewed literature, from 2015 to 2026, evaluating Holstein (6 studies, 21 treatment means) and beef × dairy crossbred steers (8 studies, 19 treatment means), as well as from commercial feedlot closeout data for beef × dairy steers from U.S. feedlots (Texas and Kansas; 17 treatment means; 2019-2022). Individual LCAs were constructed for each dataset using study-specific performance metrics, including feed intake, live weight gain (LWG), and days on feed. The assessment was conducted using a partial cradle-to-gate (limited to the feedlot finishing phase) system boundary encompassing feed production, transportation, feedlot operations, energy use, and manure management. The functional unit was defined as 1 kg of LWG to allow comparison across studies with differing experimental designs and days on feed. Statistical analyses were performed using the MIXED procedure of SAS, with treatment as a fixed effect (beef × dairy data from literature and commercial feedlot were evaluated separately) and study as a random effect. Total CO2.eq emissions per animal and emissions intensity expressed as Kg of CO2.eq/LWG were similar among genetic groups (P > 0.05). Beef × dairy steers achieved greater (P < 0.01) final body weights compared to Holstein steers without differences in dry matter intake, average daily gain, or feed efficiency. Contribution analysis indicated that feed production and enteric methane collectively accounted for 75 to 80% of total GHG emissions across all genetic groups, with similar proportional contributions among systems. The greater final body weight observed for beef × dairy steers reflect enhanced growth performance, which may contribute to improved biological efficiency in feedlot systems. These results indicate that incorporating beef genetics into dairy systems may offer environmental benefits during the feedlot phase; however, interpretation should be made with caution, given the limited number of side-by-side comparisons between straightbred dairy and beef × dairy cattle available in the literature. Furthermore, continued research is warranted to quantify system-level impact across the integrated dairy-beef value chain.