AT A 3000-cow dairy farm near Ithaca, New York, Rodrigo Bicalho wrestles a 3-week-old calf onto a scale. The calf totters about; the scale reads 52 kilograms, a healthy weight. Bicalho makes a note. He is trying to find out what happens if he gives his calves milk that, instead of being pasteurised, is treated with ultraviolet light.
