Greener fats for livestock? Evaluating the sustainability of dietary Hermetia illucens oil in dairy cow diets

This study applies Life Cycle Assessment to evaluate the environmental sustainability of using Hermetia illucens oil (HIO) instead of hydrogenated palm fat (HPF) in dairy cow diets. One kilogram of fat- and protein-corrected milk (FPCM) was chosen as the functional unit, and a gate-to-gate approach defined the system boundaries. Primary data were collected during an experimental trial conducted using Valdostana Red Pied cows. Enteric methane emissions were both measured in vitro and estimated using the IPCC model. Results showed that HIO reduces climate change impact from 1.11 to 0.99 kg CO2 eq/kg FPCM (−11%), mainly due to lower enteric methane emissions, as measured in vitro. This reduction can be attributed to the high concentrations of lauric and myristic acids in HIO, which are known to possess methane-suppressing effects. Contribution analysis revealed that enteric methane accounted for 63% of the climate change impact, followed by concentrate feed, which was the main hotspot in most other categories. Despite slightly higher resource use (fossils: +7.1%; minerals and metals: +5.5%), the overall environmental burden was 3.98% lower with HIO. The analysis using the IPCC model for estimating emissions did not report differences between the two treatments but confirmed a reduction in the overall environmental impact when using HIO (–2.26%).