Cat birthed 3 kittens. Gave away 2. Kept 1. One we kept, keeps suckling Momma cat. Milk produced. I thought this was over once surgery occurred.
Plenty of food available for cats. Momma cat staying skinny while kitten grows bigger.
Btw...my 12 year old Golden Retriever (never a mom) produced milk and thought she was the mother of the kittens. Dog and Momma cat take turns taking care of kitten.