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.