Cattle breeding herds are managed for accelerated time-controlled calving, using groups of cows predicted to calve within a period of 10 days, 1000 to 10,000 units of purified porcine relaxin are administered intramuscularly or intracervically. Auxiliary agents may also be administered such as methasone or dexamethasone. Within the selected group, parturition can be limited to time periods as short as 24 to 48 hours. Further, parturition can be accelerated from 2 to 10 days. These benefits are obtained without adverse side effects such as retained placenta or dystocia.