Clustering of feeding strategies to improve the evaluation of enteric and slurry methane emissions in dairy cows: an observational study based on Italian dairy farms

The dairy sector is facing increasing challenges in terms of its environmental impact. Methane(CH4) is a focal point of research due to its role in enteric emissions from livestock. This studyinvestigates the effects of various feeding strategies on CH4 emissions from lactating Holsteincows fed total mixed ration (TMR) silage-based diets. Four different equations for estimatingCH4 emissions were chosen according with accuracy and equation variables, and then comparedchecking whether diet composition has an effect on average emission levels. Only Mills equationdetected differences between nutritional clusters. Considering this equation on average, the CH4emissions were equal to 460.36 ± 46.95 g/d, 18.90 ± 1.57 g/kg DMI, 12.89 ± 2.83 g/kg FPCM,equal to a loss of 5.93% of gross energy intake. Clustering based on feed composition identifiedfour distinct groups of diets, with no statistically significant difference in CH4 emissions. Thehighest emissions were found in the nutritional cluster with higher fibre and starch content,with methane production (MeP) reaching 485.85 g/d, 19.47 kg/kg DMI and 14.82 kg/kg FPCM.This indicates that diet nutrients profile significantly impacts CH4 emissions, underscoring theimportance of adopting sustainable feeding strategies in dairy production. Notably, a positivecorrelation exists between MeP and milk productivity, while methane intensity negatively corre-lates with feed efficiency. The findings emphasise the necessity for context-specific emission fac-tors and underscore the importance of implementing sustainable feeding practices to mitigateCH4 emissions enhancing the efficiency of dairy production systems.