Long-term GreenFeed monitoring of enteric methane emissions in lactating buffaloes.

The GreenFeed (GF) system is widely regarded as the silver standard for measuring individual enteric methane (CH4) emissions; however, it has not previously been used in dairy buffaloes (Bubalus bubalis). This study aimed to perform long-term monitoring using the GF in lactating Mediterranean buffaloes to provide benchmark values for enteric CH4 and carbon dioxide (CO2) emissions, and CH4 emission intensity, together with a characterization of CH4 emission patterns and animal-related factors. Additionally, seasonal variation in enteric CH4 emissions was evaluated. The study was conducted on a commercial dairy buffalo farm in central Italy from June 2024 to December 2025. A GF unit was installed in the feed alley, and animals were trained to voluntarily visit the system using pelleted concentrate as bait. Fifty-four lactating buffaloes were enrolled, of which 37 voluntarily visited the GF at least once during the monitoring period. Individual milk yield, days in milk (DIM), and parity were obtained from test-day milk records. Buffaloes visited the GF 1.6 ± 0.9 times/d on average, with only six animals reaching the maximum number of daily visits. Mean daily CH4 and CO2 emissions were 337.0 ± 108.3 and 9,190.1 ± 1,543.3 g/d, respectively, and a linear positive relationship was found between the two gases. The CH4 intensity averaged 44.4 ± 19.6 g/kg of milk. Methane emissions changed throughout lactation, increasing from early lactation to approximately 120 DIM before gradually declining thereafter. A strong positive relationship was observed between milk yield and CH4 emissions. Finally, average CH4 production was greater during late winter and spring than during summer and autumn. In conclusion, these findings provide the first on-farm benchmark values for enteric CH4 and CO2 emissions in Mediterranean dairy buffaloes obtained using the GF system and highlight the importance of accounting for productive level, lactation stage, parity, and seasonal variation when characterizing enteric CH4 emissions in this species. Further studies involving larger buffalo populations across multiple commercial farms are warranted to validate these findings and support the development of robust, species-specific enteric CH4 emission factors.