# The Carbon Footprint of Milk Production on a Farm
## 3 Results and Discussion
### Main Sources of GHG Emissions, Including Sources in Milk Production
Significant differences were observed in these indicators between EU Member States. The highest shares of cattle farming in agricultural GHG emissions were noted in Luxembourg, Ireland and Slovenia (68-74%), and the lowest shares were in Greece and Bulgaria (16-27%). Figure 5: The share of the main source sectors in the GHG emissions in the EU Member States (EU-27) in 2023; the authors’ own diagram prepared on the basis of research results in the publication [36]. Total GHG emissions excluding LULUCF = 100%. Figure 6: The share of source subsectors in the GHG emissions from agriculture in the European Union in 2023, broken down by animal group (% of total agricultural emissions); the authors’ own diagram prepared on the basis of research results in the publication [8]. CRF—IPCC Common Reporting Format sector. The main sources of GHG emissions on dairy farms can be divided into three major categories: enteric fermentation, manure/slurry management, and the production and use of feed, energy and fertiliser (Figure 7). The external system boundaries encompass the production and transport of external feed, water, animals, and energy, which are used at the farm level for breeding and maintaining animals on dairy farms (Figure 8). It also encompasses the production and transport of external fertilisers, pesticides, machines, energy, and ancillary products used for growing crops or maintaining pastures on these farms (for animal feeding). This system boundary therefore refers to indirect emissions. Direct GHG and CF emissions (enteric fermentation; manure and soil management; on-farm/internal feed production and pasture management for cows) within dairy farms represent the internal boundaries of this system. Although enteric fermentation remains the most important part of the CF, the literature data indicate that emissions from other sources can contribute to more than half of the emissions in intensive production systems [22; 27; 37; 38]. The share of individual categories is determined by several factors, including the production intensification level, herd structure, technologies applied, and local determinants [23; 39]. Figure 7: Main sources of GHG emissions from milk-producing farms. According to [PERSON] et al. [41], the main CF components include emissions of methane (CH\({}_{4}\)) from enteric fermentation (resulting from microbial processes occurring in the rumen), nitrous oxide (N\({}_{2}\)O) from fertilisation and manure, and CO\({}_{2}\) from energy generation, feed and fertiliser production, and transport. It is enteric fermentation that remains the largest GHG source in milk production, accounting for as much as 40-80% of the CF [3; 12; 13; 19; 28; 42; 43]. In Brazil, enteric fermentation accounted for 60% [5], in India for 66.8% [4], while in Canada and the USA, for 44% [30; 44]. An analysis by [PERSON] et al. [37] found that CH\({}_{4}\) emissions in Canada accounted for approximately 47% of the CF. In comparison, a study by [PERSON] et al. [3], which examined 61 farms in the Po Valley, reported that methane emissions accounted for 43.3% of the CF. [PERSON] et al. [43] noted that under grazing systems, the dominant emissions originated from fermentation and fertiliser management, whereas under more intensive systems, they came from the production of feed and mineral fertilisers. Regarding extensive systems, a study conducted in Peru found that the share of enteric fermentation was, on average, 1.81 kg CO\({}_{2}\) eq kg\({}^{-1}\) FPCM of the total CF at a level of 2.26 kg CO\({}_{2}\) eq kg\({}^{-1}\) FPCM (i.e., approximately 80%) [42]. On low-productivity farms in Kenya, the emissions ranged from 2.19 to 3.13 kg CO\({}_{2}\) eq kg\({}^{-1}\) FPCM, of which approximately 54% originated from fermentation [39]. In contrast, in Mongolia (an intensive husbandry system), fermentation accounted for 18% of emissions, with a greater share noted for feed production (27%) and fertiliser management (28%) [38].