1. Introduction
Currently, reducing the environmental impact while maintaining a high production level has become an issue of particular interest worldwide. For this reason, numerous initiatives have been jointly launched among EU member states, such as the Green Deal, [
1] the Farm to Fork Strategy [
2], and the 2030 Agenda for Sustainable Development, which includes 17 sustainable development goals (SDGs) [
3,
4]. One of these goals (SDG 12) is “to ensure sustainable consumption and production patterns”, where one of the targets is to achieve sustainable management and efficient use of sustainable resources by 2030. In this context, achieving more sustainable crop and livestock production involves bringing together different approaches within the sustainable production system and its economic, environmental, and social pillars [
5]. Concepts such as eco-efficiency, which can be defined as the simultaneous ability to achieve acceptable economic outcomes with the least possible degradation of the environment, have become a highly relevant issue in the scientific and political world [
6]. Livestock activities are essential to society by supplying food, supporting rural populations and enhancing biodiversity [
7]. Therefore, the search for techniques to improve the sustainability of livestock systems should be considered an essential pivotal process in all public policies at local, national, and global levels in an attempt to address the different aspects of sustainability.
A key indicator of the optimisation of resources in agricultural systems is the assessment of technical efficiency, which measures the capacity of production units to generate the maximum output level from the optimal use of resources or inputs.
On the other hand, the growing concern for cleaner products, production, and services has led organisations and companies to pursue more sustainable methods. Consequently, several methodologies have been developed to assess the environmental impact of products, such as life cycle assessment (LCA), which stands out in livestock production systems as a method to determine the environmental impact associated with production [
8]. Data envelopment analysis (DEA) was also developed by Charnes et al. [
9] and is widely used to estimate relative efficiency and to apply to benchmark or best practice adoption techniques [
10]. It can be combined with LCA methodology in the eco-efficiency methodological framework, which is receiving significant interest as a sustainability indicator because it jointly assesses the environmental pressure of the system and the technical–economic performance of the production activity [
11].
Whether at the local or national level, eco-efficiency measurement has often been used in studies of sustainability and competitiveness improvement, both at the company and sector levels. Studies stand out, especially concerning the industrial sector [
12,
13,
14,
15], the agricultural sector [
11,
16,
17,
18,
19,
20], and the livestock sector including mixed farms [
4,
6,
7,
21,
22,
23,
24]. Environmental impact assessment studies have been carried out in Iberian pig systems [
8,
25,
26,
27], but there are no studies where economic results are maximised with the least possible environmental impact.
There is an area in the southwest Iberian Peninsula known as the
dehesa, an agro-silvopastoral system based mainly on livestock farming, agriculture and forestry in areas of Mediterranean pastures. The interactions of these activities foster a high environmental value in which the combination of management decisions promotes important environmental values such as sustainable land use, a balanced landscape, and high levels of diversity at different levels of integration [
26,
28,
29,
30].
Dehesa is one of the largest managed agroecosystems in Europe representing over a million hectares. This agroecosystem is characterized by the extensive grazing of different livestock species, with the Iberian pig being the native breed most closely linked to this area [
26,
29,
30,
31]. The Iberian pig is reared extensively in the
dehesa and uses natural resources (
Figure 1) in the traditional fattening process based on acorns and pastures, known as the
montanera.
Dehesa represents the highest concentration of production and supply of the Iberian pig sector in the European Union. In recent decades, the demand for pigs in extensive production systems has grown due to the association of these production systems with high-quality and environmentally friendly meat products [
32,
33].
Nowadays, it is a great challenge for society and for achieving sustainability to find a balance between economic performance and the use of resources. For this reason, the
dehesa is currently suffering an alarming environmental situation due to the great stress exerted on its natural resources [
26]. Therefore, it is not only essential to evaluate indicators of eco-efficiency and their production and environmental pressure reduction targets, but it is also crucial to analyse the factors that could influence the reduction of these pressures. In particular, the study at the farm level is of interest, as a large number of small-scale farms with a certain heterogeneity characterises the traditional pig sector.
This study follows an LCA–DEA approach to measure the eco-efficiency of extensive pig production in the Spanish dehesa and pursues two objectives, (i) using the LCA–DEA approach to calculate the level of eco-efficiency and (ii) to analyse the determinants of inefficiency using Tobit regression analysis. Pig farms’ social, demographic, and structural characteristics are analysed as potential drivers of inefficiency. Understanding the key determinants that lead to inefficient production units will be beneficial for improving productivity and competitiveness and promoting a more sustainable livestock production.
4. Discussion
Iberian pig production is a heterogeneous system due, on the one hand, to the fact that the volume of pig production is linked to the area of available
dehesa. On the other hand, the variability in the number of sows reflects the different intensity with which breeding is practised, from full-cycle farms that exclusively fatten the piglets produced, although with different intensities of use of the pasture, to farms where the supply of piglets for other farms is a management goal [
27]. The data obtained in terms of surface areas and pig censuses are close to other studies carried out in the
dehesa ecosystem [
26,
31,
55].
Regarding CC, the data obtained indicate that Iberian pig production is close to traditional pig production [
56], but it has greater LO impacts than other pig breed systems [
25,
56]. It could be mainly explained by the large surface area required for fattening animals fed exclusively on natural resources from the
dehesa [
57].
The approach’s selection of inputs and outputs has been performed to reflect the pig production process developed in the
dehesa synthetically. In addition, previous studies were taken into account to analyse the eco-efficiency of agricultural and livestock enterprises [
4,
11,
18,
22,
24,
35,
46]. Furthermore, the rule shown by Cooper et al. [
58] has been considered to not excessively limit the model’s degrees of freedom. The recommendation is to select a value of
n that satisfies n ≥ {m × s; 3(m + s)} where
n is the number of DMUs (35 pig farms in this study),
m is the number of inputs, and
s is the number of outputs. Therefore, the number of DMUs in our sample satisfies the rule in this study and the requirements for this methodology were met.
The level of eco-efficiency obtained is in line with previous studies on the environmental impact assessment of pig production systems, where it is highlighted that lower environmental impacts can be achieved in pig production linked to the territory using native breeds [
26]. This is due to a lower dependence on off-farm feed due to the feeding strategy of these production systems with greater use of natural resources, such as acorns available in the meadows and pastures of the
dehesa [
8,
25,
59,
60].
Regarding
Figure 3, we can conclude that the increase in LO implies a decrease in eco-efficiency levels. This is probably due to the increase in the number of pigs fattened with feedstuffs, thus increasing the hectares needed to produce raw materials for feed production. Another reason could be the low density of holm oaks and cork oaks, which impacts the surface area needed in the
montanera [
57]. Reforestation techniques in the
dehesa could positively impact eco-efficiency levels [
61].
The objective of reducing the area of
montanera while achieving the same production is possible with reforestation [
61]. An increased wooded area can be used to fatten more pigs with natural resources (acorns and grass), reducing the environmental impact and, at the same time, increasing the income as the pigs fattened with acorns have a higher commercial value. In addition, the reduction in the number of reproductive females in inefficient farms is a fact other authors have shown in the
dehesa [
29]. This is more evident for the management of multi-output systems (pig fatteners
montanera, pig fatteners
cebo campo, piglet sales).
These analysis projections reveal the maximum potential for input and environmental impact reduction that can be achieved in Iberian pig production in the
dehesa. There are no existing studies on Iberian pigs, but our sample has a better projection of improvement than other previously evaluated livestock systems, with reductions in environmental impact of more than 30% [
4,
62,
63]. Furthermore, what the above projections confirm is that it can be concluded that actions are needed to improve economic rather than environmental performance since traditional Iberian pig production systems are associated with sustainable productions based on natural resources and low environmental impact [
8,
26,
59]. Possibly these actions should be aimed at decreasing dependency on external inputs such as feedstuffs. Production systems based on fattening
montanera produce better environmental and economic benefits [
8,
33]. On the contrary, those based on fattening
cebo campo produce pigs fed with significant quantities of compound feed and a product of poorer commercial quality according to the Spanish regulations regarding the quality of Iberian pork products [
57]. However, assessing the economic sustainability of pig farms is a complex problem, as many short- and long-term factors are involved [
64].
The crucial determinants related to social and demographic aspects that positively affected eco-efficiency in Iberian pig farms was the number of children. In contrast, the variable number of years of activity and educational level, contrary to expectations, negatively affected eco-efficiency. The latter may be because more educated owners pursue higher profitability production on their farms and thus move away from a traditional production model, which, as we have found in our study, leads them to be more eco-efficient. This could also be because experienced farmers are more reluctant to change their management habits. Li et al. [
46] indicated in a study with 773 pig farms that the years of experience and dedication to the activity had a negative effect. Also, other studies focused on agriculture indicated that higher education and specialised training affected efficiency improvement [
17]. Although there is some controversy with the educational level, numerous studies indicated a positive relationship with university education, mainly because more education may imply more adaptation to new market opportunities, distancing from a traditional production model [
65]. While other studies have found an influence of age on eco-efficiency, our model did not detect any influence.
In terms of management, farm characteristics such as land ownership, livestock use, and the high proportion of pigs fattened in
montanera positively affected the level of eco-efficiency. The three factors mentioned are closely related to Iberian traditional pig production in the
dehesa where the use of natural resources is essential for developing production. There are two types of fattening on the
dehesa,
montanera and
cebo de campo. Our study shows that those farms that perform traditional management are more eco-efficient, according to results revealed by Horrillo et al. [
26] and García-Gudiño et al. [
27], mainly by optimal use of natural resources provided by the
dehesa ecosystem.
PDO certification is a quality indicator and an instrument that reduces the asymmetry of information between producer and consumer, specifying the production system [
33]. Contrary to expectations, PDO did not affect eco-efficiency, as indicated by a study by García-Cornejo et al. [
24] on livestock farms in northern Spain. In our study, it could be explained by the fact that the production of Iberian pigs is already nationally regulated [
57].
Although this method used a robust methodology to calculate eco-efficiency scores and a Tobit regression approach, the small sample size probably limited our ability to identify the most statistically significant variables. The study of the Iberian pig production systems is complex because there are different types of fattening of the animals (
montanera and
cebo campo) and in order to obtain reliable and complete data it is necessary to visit the same farm several times. Farm visits could not be carried out in the same year for all the farms, so the study was carried out over three consecutive years (2016–2018). This fact adds a bias which, in principle, should not be relevant because prices of inputs and outputs remained stable, but should be taken into account for further studies. Future studies should emphasise larger samples of production units from different locations to understand better the role of other factors, such as management, information use, and decision-making process [
66,
67]. Despite these limitations and the sample size, our study has contributed to the existing literature as the first study on eco-efficiency in Iberian pig farms in the
dehesa ecosystem.
5. Conclusions
In this study, an evaluation of the eco-efficiency of Iberian pig farms in the dehesa area of the Iberian Peninsula has been carried out. The application of a combined LCA and DEA methodology of Iberian pig farms based in the dehesa area of the Iberian Peninsula has proved to be a valuable tool for the comparative assessment of environmental, technical, and economic parameters. The Iberian pig farms in the dehesa showed a high level of eco-efficiency, suggesting that the average farm could decrease its climate impact given the level of inputs and production technology, provided that the farms adopt the observed best practices. The farmer’s professionalism and profile influences eco-efficiency. Other farm characteristics related to natural resource use, and the proportion of pigs fattened in montanera affected the level of eco-efficiency.
The production of Iberian pigs following traditional management systems is more eco-efficient and has a lower environmental impact, increasing its impact as it moves towards a fattening system in montanera. The reduction of environmental impact implies a reduction in the consumption of feedstuffs. Therefore, better management of natural resources and adapting production to the type of farm could reduce feedstuff dependency and make traditional Iberian pig production more environmentally friendly and eco-efficient.
Finally, it should be noted that the results of our study are of interest to stakeholders and policymakers to identify the most environmentally friendly practices to optimize resources on Iberian pig farms. Policies should be aimed at promoting the system of production of Iberian pigs in the montanera. The results can be used to implement cleaner production strategies that reduce national emissions. Furthermore, future research could be carried out to evaluate this eco-efficiency model in other species that grow in the dehesa in order to improve the conservation of this ecosystem.