How to send email on birthday ?

global class BatchWishes implements Database.Batchable<Employee__c> {
     global Iterable<employee__c> start(Database.BatchableContext bc){
     list<employee__c> sq=[select name,empname__c ,Email_Id__c from employee__c where Date_of_Birth__c=today];
    return sq;
    }
   global  void execute(Database.BatchableContext bc, List<employee__c> lst)
      {
list<Messaging.SingleEmailMessage> mail = new list<Messaging.SingleEmailMessage>();
        for(employee__c e: lst)
        {
         Messaging.SingleEmailMessage maileach = new Messaging.SingleEmailMessage();
         list<string> toadd=new list<string>();
         toadd.add(e.Email_Id__c );
          maileach.settoaddresses(toadd);
          maileach.setsubject('birthday wishes');
          maileach.setplaintextbody('happy birthday '+e.empname__c);
          mail.add(maileach);
        }
    Messaging.SendEmailResult[]  result  =Messaging.sendEmail( mail);
    } 
   global  void finish(Database.BatchableContext sc) 
    {
      system.debug(sc);
    }
}

global class BirthdayNameOptions implements Schedulable{
global   void execute(SchedulableContext dc){
//batch class name   
 BatchWishes bth=new BatchWishes ();
    Database.executeBatch(bth,20);
    }
}