Ecological efficiency of hog scale production under environmental regulation in China: based on an optimal super efficiency SBM-Malmquist-Tobit model

China's hog production is facing the dual pressures of the market and environment. A systematic analysis of the ecological efficiency (eco-efficiency) of hog cultivation is of great significance for the development of sustainability and distribution optimization in the industry. This paper investigates the eco-efficiency of hog production and the determinants of eco-efficiency in China using panel data (2004-2018). An optimal super efficiency slacks-based measure (SBM)-Malmquist-Tobit model is adopted for hog production analysis, and the empirical results show a great variation in eco-efficiency across provinces, ranging from 0.557 to 1.19 with a mean value of 0.937 in 2018. The predominant production area of hogs is found being transferred from north to south, with small- and medium-scale predominant production areas shifted from East China to Southwest China, and large-scale predominant production areas shifted from North China to South Central China. Another finding is that eco-efficiency increased by the improvement of technical efficiency. In addition, the Tobit regression results show that rural economic development, the government's investment in environmental control, the market advantage index, and transportation conditions had positive effects on the eco-efficiency; meanwhile, the forbidden policy for livestock cultivation in certain areas, the structure of the hog breeding industry, the density of slaughtered fattened hogs, and the prices of hogs had negative effects on the eco-efficiency.