Goats or pigs? Sustainable approach of different raising systems fed by maize silage

The ecological livestock husbandry tends to be popular in China but the real situation is many models appeared without scientific analysis. And very limited theoretical researches compared ecological breeding systems and livestock species on environmental and economic and carrying capacity aspects. To choose the best pig-raising method and compare it with the goat raising system, this study combined emergy evaluation methods and economic analysis methods and livestock carrying capacity evaluation methods to gain the objective results. Pigs raising systems all performed little weaker than the goats raising system in the environment-friendly aspect. But the pigs raising systems were good at the aspects of economy and livestock carrying capacity. The 80% maize silage added fodder in the pigs fattening period (Pig-raising system Group A (PA)) performed excellently. The yield-based economic profit (Py) and profit rate (BCR) of PA increased by 2%–13% and 7 %-48%, respectively, compared to the other two pig-raising systems (Pig-raising system Group B (PB) & Group C (PC)). Meanwhile, the emergy yield ratio (EYR) and the emergy loading ratio (ELR) of PA were 0.2%–2% and 1%–3% lower than the other two systems (PB&PC), respectively. And emergy sustainability index (ESI) of PA was about 1% better than PB and PC. Furthermore, the livestock carrying capacity based on planting area (L1) and fertilized area (L2) of PA performed 18%–210% and about 14% better than PB and PC, respectively. To some extent, pigs could tolerate extreme high concentration of the maize silage added into the fodder. Moreover, a high concentration of maize silage added to the fodder of pigs did not result a sharp drop in the yield. On the contrary, the higher concentration of maize silage added to the fodder increased more economic benefits and gained more sustainability and improved the livestock carrying capacity of the ecological pigs raising system.