What is the name of the first milk ejected when breastfeeding?

The first milk humans (and most other mammals) make is called colostrum. Colostrum is thicker and has a more yellow colour than regular milk and is full of all sorts of antibodies and nutrition to get baby off to a healthy start. It is higher in protein and is designed to sustain and protect the baby until the breastmilk comes in, usually about day 3-4. It is only there in small quantities but is very rich and is loaded with nutrients and immunity-boosting compounds to fuel and support the baby in their first few days of life.

Colostrum also has a mild laxative effect, encouraging the passing of the baby's first stool, which is called meconium. This clears excess bilirubin, a waste-product of dead red blood cells, which is produced in large quantities at birth due to blood volume reduction from the infant's body and helps prevent jaundice.

This first stage of breast milk production begins during pregnancy and lasts for several days after the birth of the baby. Even though all mammals produce colostrum, supplements are usually made from the colostrum of cow's. This supplement is known as bovine colostrum.