The USDA is announcing the largest recall of ground beef in U.S. history: 143 million pounds, most of it already sold and, presumably, eaten. The meat was produced at the Westland/Hallmark Meat company in Chino, California. The recall follows a shocking video of an investigation by the Humane Society at that plant. The video, which is not easy to watch, shows “downer” cows being slaughtered for food as well as other violations of regulations for meat slaughter. The USDA is taking this very seriously, if too late to keep the meat out of the food supply. It has posted answers to Frequently Asked Questions on its website, along with a transcript of a technical briefing, and links to related statements. And here’s what today’s New York Times has to say about it (as always, the writer, Andrew Martin, provides great quotes). If you are puzzled about what humane treatment of farm animals might have to do with the safety of the meat we eat, here is as good an explanation as anyone could ask for.