My breast feeding baby is 13 month old.do we need to give cows milk at this stage?

Yes: The benefit of breastfeeding over other milk sources wains after 8-9 mo & a kids diet has shifted to include solids. At a year or later cow milk is an easily obtained rich source of the calcium,fat & protein they need. Try to limit the maximum intake too 16-24 oz/d to avoid gut irritation that comes with excess.

Breastfed: Congratulations on successfully breastfeeding past a year! This is a wonderful achievement. If the question is can you continue breastfeeding, you certainly can. There is not a "need" to give cows milk, although it is helpful socially (all the other kids are drinking a cup of milk and having a cookie). If baby is eating solids and drinking from a cup, sounds very healthy.