the annual growth rate of swine farming is estimated
to be about 100% in recent years. Based on the historic data
and the rough annual growth rate of 100%, it is estimated that
approximately 15 million pigs had been raised in the CAFO zone
by the end of 2012. According to the typical swine feed formula,
each tonne of feed contains 45–100 g of ASA (mean 80 g, or 28 g
As),