Life Cycle Assessment Of Large-scale Pork Production Systems

Growing populations and incomes,along with changing food preferences,are rapidly increasing demand for livestock products,especially in developing countries.To meet the increasing demand for livestock and poultry products,many countries including China,began to use more intensive crop livestock production instead of traditional small-scale farming.At the same time,the livestock sector emerges as one of the top two or three most significant contributors to the most serious environmental problems,at every scale from local to global.Pork is one of the most important livestock products,and now 38.5%of the total pork production has come from large-scale pig farms in China,and this proportion is very likely to increase in the future.Contribution to environmental problems caused by large-scale pork production is on a massive scale and the potential contribution to their solution is equally large.The impact is so significant that it needs to be addressed with urgency.Hence,the study quantitatively assesses the life-cycle environmental impacts of a large-scale pork production system and identifies the potential opportunities,which can help promote sustainable development of the livestock industry.Based on literature review,expert consultation and field investigations,the study applies the methodology of life cycle assessment(LCA)"from cradle to gate" to define the system boundary of the large-scale pork production system,which includes feed production,piglets production(PP),growing to finishing(GF),manure management(MM),and slaughterhouse(SH).On this basis,we established the evaluation model of large-scale pork production system with the software Gabi 6.0 and the Ecoinvent database.The life-cycle environmental impacts were evaluated quantitatively with the ReCiPe(H)v.1.07 method.Various impact categories are used,including Climate change(CC),Fossil depletion(FD),Water depletion(WD),Terrestrial acidification(TA),Freshwater ecotoxicity(FET),Human toxicity(HT),Terrestrial ecotoxicity(TET),Agricultural land occupation(ALO)and Freshwater eutrophication(FE).The results indicate that feed production,growing to finishing and manure management have higher impacts compared with other phases.The production of maize in feed for GF is the hotspot(contribution>10%)for 7 different impact categories,and its contribution accounts for more than 30%to WD,TET,and ALO.The production of soybean meals in feed for GF also contributes 36.39%to ALO.The production of electricity consumed in GF phase is also hotspot for 5 impact categories.The NH3 discharged in GF contributes 12.37%for TA.Manure management is hotspot for 6 impact categories,which contribution accounts for 87.53%and 81.29%for FET and FE,and more than 40%for both HT and TET.This is mainly due to the emissions of phosphorus and heavy metals to soil and freshwater during MM.The transportation of swine before slaughterhouse is also a hotspot for FD.Based on the assessment results,the study uses hierarchical pattern to identify the factors which have significant environmental impacts as hotspots by analyzing the each process and elementary flow throughout the whole life cycle of the large-scale pork production system.The hotspots are potentially the areas where the environmental performance can be mostly improved.Additionally,the study puts forward some advice for future improvement,such as:optimization of feed crops and animals feeding patterns,reducing fertilizer inputs and nutrient loss caused by chemical fertilizer application,improvement of feed utilization;Optimizing energy structure and reduce energy consumption caused by transport and electricity;improving dietary structure and manure management,promoting the rational utilization of manure recycling;improving the structure and equipment of pig houses,reducing the environmental impact of pig-breeding.