The plight of beef cattle has been well-documented: a majority of meat cows in the United States are raised quickly on unnatural grain-based feedlot diets before being slaughtered. We don't hear that much about dairy cows, though. Thus, the graph above surprised us enough to run our second USDA "chart of the day" in a row: it turns out that while the number of milk cows in the United States has decreased by a couple of million since the mid-eighties, the amount of milk produced per cow has almost doubled in that time frame. According to the USDA, these parallel trends should continue through 2020.

How did this happen? The USDA says the increase in the productivity of milk cows can be attributed to various technological and biological developments. Genetic science has improved the breeding of milk cows, farms increasingly understand how to provide better food and nutrients to cows, and technological shifts like the switch from hand to mechanical milking have also contributed to increased output, says Don Blayney, an agricultural economist at the USDA Economic Research Service. "It's a long term trend," said Blayney, "it's a chart that has looked the same forever."

At a glance, this appears to be a success story for industrial agriculture, as Blayney seems confident that the quality of the milk was unchanged over the years, saying that studies have shown no significant shift in nutritional content. At the same time, the USDA report notes the connection between the downsizing of milk herds and the loss of smaller and more diversified farms. Big agriculture opponents probably still have fodder for complaints.