The GHG emissions of the SECBP farm system amounted to 12.6 kg CO₂eq./kg live meat gross production (LMGP). When accounting for the carbon storage contribution of −0.8 kg CO₂eq./kg LMGP, the total carbon footprint for the SECBP system was 13.4 kg CO₂eq./kg LMGP. Applying the same methodology to the IFCF farm system, the GHG emissions were 19.0 kg CO₂eq./kg LMGP, while the carbon storage contribution was −0.2 kg CO₂eq./kg LMGP. Consequently, the carbon footprint of the IFCF farm system was 19.2 kg CO₂eq./kg LMGP. Comparing the two carbon footprints revealed a difference of 5.8 kg CO₂eq./kg LMGP in favor of the SECBP model. The IFCF system had a higher CF by 43.3% (Figure 2).

The data we obtained were compared with those found in the literature. However, it is important to highlight that discrepancies may arise due to different calculation methods, variations in production system characteristics, and regional differences. Nonetheless, the analyzed studies consistently showed the same differences between intensive and extensive systems. Previous empirical evidence highlighted CF values for the beef industry ranging from 16.4 to 10.4 kg CO₂eq [40], indicating a slightly higher value compared to other studies for IFCF. However, the literature confirmed the differences in emission reduction between intensive and extensive farming systems. The authors in [17] reported lower values in both cases compared to this study with 11.18 kg CO₂eq for small and intensive farming and 6.02 kg CO₂eq for extensive farms. The authors in [7] reported better results in terms of CF for extensive production system with 10.2 kg CO₂eq./kg of live weight while intensive production system showed 37.6 kg CO₂eq./kg of live weight. However, the same authors analyzed GHG emissions using two functional units: carcass weight (CW) and live weight (LW). Emissions based on CW and LW were compared, considering that CW is the product of LW and DP (CW = LW × DP), where DP represents the dressing percentage, which varies depending on the type of feeding (grass-finished or feedlot). These authors selected 32 studies that represented 115 scenarios, 19 of which also considered carbon sequestration.

This result aligns with other sector studies, as grass-fed systems rely on diets rich in fiber, which require more ruminal fermentation and increase methane production compared to concentrate-based diets [22]. In the IFCF system, the cattle’s diet included a concentrate constituting 45% of the total feed ration. Additionally, the feed consisted of 37% soybean meal, enabling a good growth rate. In the IFCF farm system, the largest contributor was the “food” category, representing 54.7% of the carbon footprint, due to the high quantity of purchased animal feed. In this case, the trend is opposite to the previous one: the SECBP system recorded a value of 0.1 kg CO₂eq./kg LMGP due to the purchase of small amounts of salt and dehydrated hay, whereas the IFCF system showed a value of 10.5 kg CO₂eq./kg LMGP, which represents the main component of the CF in this system. This is due to the emissions from the production and transportation of these feeds. Comparing these two categories, which were the primary contributors to the CF of the two systems, it is evident that the SECBP system is more advantageous, despite the slower animal growth and, consequently, longer rearing times. Generally, animals raised in grass-fed systems grow more slowly and require more days to reach slaughter weight. This prolongs the fermentation period and increases the total methane produced per animal [22].

This study also considered the carbon sequestration capacity. Both systems have a negative value of carbon storage. This means that, in both cases, there is a loss of soil C rather than an accumulation. However, IFCF is more virtuous because, in this system, there are areas cultivated with self-consumed cereals (maize). These areas are positively evaluated by CAP’2ER^® in the calculation of carbon storage. IFCF also has a small area managed with permanent grassland, which marginally contributes to carbon storage. In IFCF, the loss of C from the soil contributes 1% to the total carbon footprint. SECBP has larger areas dedicated to temporary grassland and hedges. These crops allow one to increase the stored C. However, it does not grow cereals for animal feed, and therefore, CAP’2ER^® negatively calculates carbon storage. This led to a net loss of stored carbon equivalent to 0.8 kg CO₂eq./kg LMGP, which exacerbated the CF. Indeed, 6.0% of the carbon footprint was attributed to the loss of stored carbon. However, in recent studies, AMP grazing has been proposed as a grazing management system that enhances soil carbon storage [19,49].

However, the studies found in the literature highlighted that AMP systems can sequester carbon. The authors in [19] reported a carbon sequestration rate of 3.59 Mg C/ha/yr over four years of AMP. When SOC was included in GHG footprint estimates, finishing emissions for the AMP system decreased from 9.62 to −6.65 kg CO₂eq./kg CW, whereas feedlot-finished (FL) emissions showed a slight increase from 6.09 to 6.12 kg CO₂eq./kg CW due to soil erosion [19]. Nonetheless, these differences may also be attributed to regional disparities, different calculation methods, and the specific characteristics of the production system.

From the sales price data we collected (Table 1), we found that the SECBP farm can sell its animals at an average price of EUR 6.83 per kilogram of live weight, while the IFCF farm can sell its animals at an average price of EUR 3.68 per kilogram of live weight. By relating the CF with the sales price, it was possible to calculate the carbon footprint, using the monetary value of beef as the functional unit. SECBP produces 1.96 kg of CO₂eq/EUR, while the IFCF produces 5.22 kg of CO₂eq/EUR, confirming the trend identified in the previous analysis in which SECBP had the better performance in terms of CF.

The only article found that refers to the monetary value is that of [7], which, as previously mentioned, presents a different methodology in the selection of case studies. The authors in [7] observed that the GHG emissions based on monetary value range from 9.7 (grass-finishing) to 31 (feedlot beef) kg of CO₂eq./MU (monetary unit). However, the authors calculated the monetary value as the functional unit by setting the average price of intensively produced beef as the reference unit (1 MU) and determining the monetary value of extensively produced beef as the average premium above the reference unit, considering that the price paid for grass-finished beef between 2014 and 2021 varied depending on the cuts, ranging from 48% to 193%. The authors in [7] also found that extensive production (grass-finishing beef) produced greater weight-based, but lower value-based, GHG emissions than intensive production (feedlot-finishing beef). They explained these findings by noting that extensive production requires more time to reach slaughter weight compared to intensive production, during which they produce GHG emissions. However, the beef produced in an extensive system also has a higher market price than beef produced in an intensive system, which results in lower GHG emissions when measured in value terms [7]. Nonetheless, only a quarter of their study sample included carbon sequestration in their emissions estimation. The reason for this could be attributed also to the fact that SECBP is not entirely an extensive farming system but it could be better associated with a semi-extensive farming practices or AMP grazing. The herd’s feeding is managed daily by rotating the animals through paddocks planted with grass forage, ensuring access to fresh forage at the optimal stage of maturity each day. The animals are moved from one paddock to another daily. Any forage shortages during the winter season are addressed using dry forage. Although this management approach does not achieve the growth rates of the IFCF system, it makes the SECBP system more efficient than simple extensive grazing. Therefore, to determine whether weight-based functional units favor intensive systems with high feed conversion efficiency and monetary value-based functional units’ reward systems that produce higher market value meat, such as grass-finished beef, it is necessary to delve deeper into the literature on this topic. The goal should be to determine whether, as stated by [7], the longer lifecycle of animals in extensive farming, compared to intensive systems, generates higher emissions in weight-based terms. The increase in the price of extensively produced beef, as highlighted by [7], could contribute to a reduction in consumption in developed countries, with potential benefits in terms of public health and emission reduction. However, this dynamic could negatively affect economic accessibility to the protein generated by meat, underscoring the need for a global and balanced approach to the transition towards more sustainable systems.