Why it is advisable to breast feed the baby for first few weeks

Why it is advisable to breast feed the baby for first few weeks? 

Why Colostrum is good for infants? 

Answer: Infants or babies after birth do not have strong immune system. The colostrum or mother's milk contains many antibodies which provides passive immunity to the babies. 

Therefore it is advisable to breast feed the baby for first few several weeks.