# The Carbon Footprint of Milk Production on a Farm
## 3 Results and Discussion
### Farm Scale and Its Characteristics  
The scale of a farm and its organisation and integration levels are significant determinants of the GHG emission levels per milk unit. It has been observed in many regions of the world that larger, better-organised production units achieve a lower CF value as compared with small, low-productivity farms. In Turkey, according to [PERSON] and [PERSON] [56], the CF for small dairy farms was, on average, 1.35 kg CO\({}_{2}\) eq kg\({}^{-1}\) FPCM, whereas for large mechanised farms it was lower, amounting to 1.13 kg CO\({}_{2}\) eq kg\({}^{-1}\) FPCM. Similar trends were observed in Brazil, where larger farms utilising modern technologies and improved management achieved lower CF values than smaller traditional farms [23]. In Central America, [PERSON] et al. [57] demonstrated that farms with a greater production scale, which used technical advice and applied more efficient fertilisation and feed management systems, achieved noticeably lower CF values as compared with farms unsupported by advisory systems. Moreover, access to expert knowledge enables the adaptation of emission-reducing practices. In a subsequent publication, the same authors [17] noted that smaller farms were characterised by higher sustainability levels when their activities included additional environmental functions, e.g., agroecological cultivation, water retention or local production of organic fertilisers. A study by [PERSON] et al. [15] conducted in India indicated the complexity of assessing the impact of small farms on the climate. The average herd size in that study was only four head of cattle, and the initially measured CF for milk was 2.2 kg CO\({}_{2}\) eq kg\({}^{-1}\) FPCM. However, after considering manure production and its role in closing the nutrient cycle, the corrected CF value dropped to 1.7 kg CO\({}_{2}\) eq kg\({}^{-1}\) FPCM. This shows that the environmental assessment of multifunctional farms requires a systemic approach, taking into account ecosystem services and non-production benefits. The reason for the higher CF of small farms is, usually, lower feed conversion efficiency and a higher share of emissions from purchases of high-protein feed, often imported and affected by additional emissions associated with transport and the LUC index [3]. Additionally, these farms are often characterised by lower fertilisation management levels and higher N losses into the environment. In contrast, [PERSON] et al. [14] emphasised that the feed conversion efficiency is one of the most important emission-reducing factors, irrespective of the production scale. Better feed utilisation results in lower CH\({}_{4}\) emissions and lower amounts of manure requiring further treatment. Another significant factor differentiating farms is the level of integration of the production system, which is understood as feed self-sufficiency, production of organic fertilisers, and internal closure of the nutrient cycle. Studies by [PERSON] et al. [45] and [PERSON] et al. [46] demonstrated that farms applying manure composting, using renewable energy sources (RES), e.g., from biogas plants, and using pastures in a rotational manner showed lower total CF values compared with farms relying on external energy and feed sources. An interesting observation was also presented by [PERSON] et al. [18], who highlighted the importance of social factors, such as the level of farmers' education, access to advisory services, and the level of work organisation, as indirect CF determinants. An analysis of Italian systems showed that family farms, despite their smaller scale, often achieve better environmental results thanks to their greater commitment and flexibility in terms of decision-making. In turn, [PERSON] et al. [51] pointed out that smaller farms in Ethiopia were characterised by a high CF variability determined by the level of local resource utilisation and labour efficiency.