| Pig breeding industry is the leading industry of animal husbandry in Hubei Province.There were 42,33,6100 heads of marketed pigs in 2016,which ranked the fifth in China: the pork output(yield)reached 3,212,000 tons.Depending on the authorized data,Hubei province has 781 large-scale pig farms,ranking the first in China.In 2014,the market share of scale production reached 76% in Hubei province—nearly 10 points more than the national average.Over 50 thousands large scale pig farms showed an increasing trend.The waste product in the whole process of production has caused serious influence to the air,water,soil and other ecological environment,and has become an important restricting factor on the development of the pig breeding industry.Therefore,in raising the efficiency of pig breeding,we should pay more attention to its sustainable development.Life Cycle Assessment(LCA)is an important measurement of sustainable development and an effective tool for environmental management.It was applied to evaluate the pig production system.It includes both the environmental impact of waste production and the environmental impact of inputs.It is an important way to reveal the environmental impact of the key links and key factors of pig production,and to evaluate the environmental impact of different farming patterns.Firstly,the LCA model of pig products was constructed.Using the model,the types and leading materials selection of typical pig houses were evaluated.And the influence of pig production system and fecal disposal methods on the environment was also evaluated.The model was used to evaluate the environmental impacts of the main pig farming models in Hubei Province.Finally,the ecological efficiency method was used to further study the total ecological cost and Eco-efficiency of the unit product under the different production mode of pig in Hubei Province.The research contents and results are as follows:1.The evaluation model of pig production system was constructed according to the national standard GB/T24040-2008?environmental management life cycle assessment principles and framework?.The system boundary and scope is determined.The pig production process divided into piglet raise,feed consumption,building materials,daily management,sewage treatment five key link.In the model based on pig production process continuity,function,relative independence,the main production stage characteristics and corresponding material input type.2.It evaluated the environmental impact of piggery by application of SimaPro(Version7.1)software,combined the evaluation index system of IMPACT2002+ method.The pigsty is divided into semi open pigsty and closed pigsty.combined with the bearing structure,the pigsty are divided into the brick structure pig house which semi closed using roller shutters,the light steel structure pig house which semi closed using roller shutters,the brick structure pig house which closed by windows and the environmental protection materials pig house which closed by windows.The main building material is sand,cement,steel,wood,brick,benzene plate,watts.One of the new environmental protection building materials for blast furnace slag cement,sand autoclaved fly ash brick,cement tile.Function units are defined as length * width * height of 40m*8m*2.5m,building area for 320m2 of single pigsty;System boundary as pigsty materialization stage.The environmental impact of four kinds of structure: the closed brick structure pig house using roller shutters(9.52)<the closed environmental brick structure pig house using windows(9.69)<the closed brick structure pig house by windows(10.36)<the light steel structure pig house which semi closed using roller shutters(11.14).So the closed brick structure pig house is propitious to environmental protection.And the environmental material's pigsty is more propitious to environmental protection than additional material's pigsty.But the closed light steel structure has most influences.3.The effect of two kinds methods of sewage treatment,using the aerobic compost and anaerobic fermentation production on the environmental influence,was studied by the evaluation index system of Eco-indicator99 method.The function unit is 1t fresh pig manure;Life cycle process of aerobic compost includes feces collection,manure mixed composting process,ventilation,drying and ripening of waste disposal process.The system boundary of anaerobic fermentation process includes anaerobic fermentation stage,cooking stage,biogas residue treatment stage.The results were as follows: the environment score of aerobic compost process is 4.65 points.the environmental score of anaerobic fermentation process is 1.11.So sewage treatment by anaerobic fermentation method is propitious to reduce environmental impact.4.The effect of three kinds of pig production system in Hubei province as a whole and the key link on the environmental influence was studied by the evaluation index system of Eco-indicator99 method.10 thousand heads,50 thousands heads,the size of households(150 heads)three scale production system was choice as the research object.It was adopted here that the evaluation model was constructed in the second chapter;function unit is 100 kg commercial pig;the detailed list of input function unit use the field measurement and literature data collection.The field measurement of piggery specifications,identify the type of building materials,investigation of swine population structure,water consumption,power consumption,consumed feed and manure treatment.Results as follows:(1)The single score of environmental burden of the three pig farming systems are 40.05 point for ten-thousand size system,41.45 point for fifty-thousand size production system and 39.92 point for household production system relatively.There is no significant difference.(2)The three ?endpoint" categories account for proportion in the single score.Human health accounts for 19.17%,ecosystem quality for 63.17%,and resource consumption for 17.66% in ten thousand sizes of pig production system.Human health accounts for 22.16%,the ecosystem quality for 63.55%,and the resource consumption for 14.29% in fifty thousand sizes of pig production system.Human health accounts for 14.88%,ecological system quality for 59.41%,resource consumption for 25.71% in household farming system.(3)The contribution of key links to environment score of the whole production system successively are: the consumption of feed,piglets,daily management,sewage treatment and the consumption of building materials;The proportion of pre-weaning(18.23%)is less than the proportion after weaning(81.77%),it indicates the environmental impact of fattening stage is greater(4)It is showed that the environmental impact score of piglets' production is significantly negatively correlated with the number of weaned piglets.The environmental impact score of piglets' production affected by the reproductive performance of the sows.(5)We show that the contribution of unit process to single score of three scale production systems,the contributions of larger process to the environmental impact are the process of maize and wheat straw counters-field wet compost,corn and wheat planting and processing phase,and N fertilizer application process.5.The Eco-efficiency of the three-scale production system from economic benefits is analyzed.With SimaPro(Version7.1)software obtained the input data of material,energy and waste emission of three kinds of production system,combined Eco-costs 2012 database,the ecological efficiency = product or service value / ecological cost *100 formula to calculate the ecological efficiency of three the scale of production system.The total ecological cost per 100 kg of ten thousand scale,fifty thousand scale and households three pig production systems,was 1067.11120.2 and 1024.2,respectively,and the corresponding ecological efficiency value was 131.2%,125% and 136.7%.Eco-efficiency value is smaller,showed that each unit of output has a greater impact on the environment than the product or value of the product.Therefore,it can be judged that the fifty thousand-scale production system is the most influential on the environment,followed by 10 thousand-scale production systems,and the household production system has the least impact.In summary,the brick structure pig house which semi closed using roller shutters advantageous to reduce the environmental impact.The anaerobic fermentation method has more conducive to reduce the environmental impact.Environmental impact of the household production system is greater than ten thousand sizes of pig production system and fifty thousand sizes of scale production system,but it has no obviously difference.However,according to the environmental score and the value of the Eco-efficiency,the appropriate scale of the household production system is more conducive to environmental protection.The environmental impact of fattening pigs is greater than the piglet production.It is showed that the environmental impact score of piglets' production is significantly negatively correlated with the number of weaned piglets.The environmental impact score of piglets' production affected by the reproductive performance of the sows.Therefore,the best way to reduce the burden of intensive pig farming systems on environment in Hubei province is to improve the reproductive performance of sows,feed conversion rate,the yield of crops and the utilization ratio of manure;on the other hand,the method is to reduce the consumption of chemical fertilizers and the dosage of pesticides. |
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