Highly unpleasant and negative are the raw, uncomposted, intense smells that emanate from concentrated animal feeding operations, or CAFOs, which confine and raise large numbers of animals—hundreds, thousands, hundreds of thousands—in a small area, and have come to dominate modern meat and dairy production over the last few decades. They accumulate huge quantities of excrement that can be smelled from miles away. I live in central California and pass by the Harris cattle ranch on Interstate 5 near Coalinga whenever I drive between San Francisco and Los Angeles. Even with the car windows closed, I can smell it long before I see it. Tens of thousands of beef cattle are confined there, each animal generating some 65 pounds of urine and excrement a day. Today’s formulated feeds usually supply more nitrogen than the animals would obtain from their natural diet of plants, so their excrement is especially rich in the most offensive volatiles, the branched acids, cresol, skatole, ammonia, and amines.