In babies, gastrocolic reflex is usually strong.
The gastrocolic reflex is a reflex in which the act of eating stimulates movement in the gastrointestinal tract, result in stronger intestinal contractions.
Many times babies pass motion after feeding immediately. It is normal in babies.
But make sure she is not dehydrated.
continue giving ORS
by spoon and continue breastfeeding
if baby dehydrates / become sluggish/ pass blood in stool
/ mass in abdomen if becomes palpable.
I hope I answered your query. In case of doubt I will be happy to help you.