Breast milk to cows milk?

Elisabeth • 27. Married💍. Cardiac RN❤️. Fur momma 🐾🐾. 1/15/19Logan💙

How early have some of you transitioned your babies from breast milk to cows milk? My son just turned 10 months. My milk supply is dropping, and I have enough frozen breastmilk to probably make it to 11mo, I just don’t want to have to transition him from breast milk to formula to cows milk. Has anyone given there baby cows milk before 12mo?