Life-cycle comparisons of economic and environmental consequences for pig production with four different models in China

China, the world's largest consumer and producer of pork in the world, is attracting increasing attention due to the environmental impacts of its pig production. Previous studies seldom comprehensively compare the environmental impacts of the pig production system with different models, resulting in different intensities of environmental impacts. We aim to comprehensively evaluate Chinese pig production with different breeding models and explore a more sustainable way for pig production. We use life cycle assessment (LCA) to evaluate and compare environmental impacts of pig production system with four main breeding models in China from 1998 to 2020: domestic breeding, small-scale breeding, medium-scale breeding, and large-scale breeding. The life cycle encompasses fertilizer production, feed production, feed processing, pig raising, waste treatment, and slaughtering. The impact categories including energy consumption (EN), global warming (GWP), acidification (AP), eutrophication (EU), water use (WD), and land occupation (LO) are expressed with "100 kg live weight of fattening pig at farm gate." The results show that driven by governmental support, growing meat demand, and cost advantage, the scale breeding especially large-scale breeding simultaneously yielded greater net economic benefit and less environmental impact compared to other breeding models especially the domestic breeding. Due to mineral fertilizer application, feed production contributed over 50% of the total environmental impacts. Notably, the composition of feeds exerted significant influence on the environmental impacts arising from fertilizer production and feed processing. Furthermore, attributable to the substantial use of electricity and heat, as well as the concomitant emissions, pig raising contributed the largest GWP, while ranking second in terms of AP and EU. Notably, waste management constituted the third-largest EU, AP, and WD. In addition to promote scale breeding, we put forth several sustainable measures encompassing feed composition, cultivation practices, fertilizer utilization, and waste management for consideration.