Abstract Varying amounts of lactose were fed to 24 male Holstein calves (six per group) from 3 to 77 days of age. Rations were: 1) Hay-grain (after weaning from whole milk at 5 wk); 2) whole milk; 3) whole milk plus 5% lactose (on a milk weight basis); and 4) whole milk plus 15% lactose. At biweekly...