Free-range acorn feeding results in negative carbon footprint of Iberian pig production in the dehesa agro-forestry system

Abstract

Iberian pig production has its own quality regulation, which defines different handling and feeding systems for this breed. These differences influence production costs, market price and environmental impact. The most extensive system of fattening Iberian pigs is based on foraging acorns in a silvopastoral system named dehesa, and consumers usually associate the Iberian pork with this system, although nowadays more intensive systems are dominant due to their productivity and management simplicity. The aim of this study is to assess the Carbon Footprint (CF) of the different Iberian pig production systems using the Life Cycle Assessment (LCA) methodology.This study is based on data collected from 19 Iberian pig farms producing nursery growers (≤25 kg, 2 farms), pre-finished pigs (100–110 kg, 3 farms) and 3 types of finished pigs (150–175 kg), including free-range fattened pigs (17 farms), outdoor intensively fattened pigs (2 farms) and indoor intensively fattened pigs (2 farms). The CF was calculated with a “cradle to farm gate” approach using the kg of live weight (kgLW) as functional unit, and including C sequestration in soils and biomass, which was calculated by field monitoring in a selection of measuring points. The average CFs of the final products were 9.2 ± 2.5 kg CO2eq kgLW−1 for nursery growers, 5.6 ± 2.42 kg CO2eq kgLW−1 for pre-finished pigs, −5.6 ± 6.5 kg CO2eq kgLW−1 for free-range fattened pigs, 3.1 ± 1.5 kg CO2eq kgLW−1 for outdoor intensively fattened pigs and 7.7 ± 0.3 kg CO2eq kgLW−1 for intensively fattened pigs. The main C sinks of the dehesa system (trees and soil) sequestered an average of 3.18 t CO2eq ha−1 year−1. This C sequestration, averaging −10.2 ± 6.7 kg CO2eq kgLW−1 in free-range pig production, offsets 223% of the GHG emissions in those systems, which resulted in a negative CF (net CO2 sequestration). There was a direct relationship between CF and pig stocking rate, leading to strongly negative CF values on those farms with the lowest pig stocking rates.