Wouldn't have thought you'd make much money from them, input is expensive for calves. I'd feed milk twice a day, id asume they would be on two litres of milk at present? always allow access to clean fresh water, ventilation is a big thing for calves, access to cake but don't give them so much that they waste it all, don't start wean from milk until they are eating at least kg of cake. Keep everything very clean. What sort of health status is the farm/herd? Do they lose many calves, if o why? Read up on common issues and illnesses, calves can get very Ill very quickly.