Lactational changes in the N-glycoloylneuraminic acid content of bovine milk gangliosides.

The N-glycoloylneuraminic acid (Neu5Gc) contents of milk and milk gangliosides from bovines were investigated during the different stages of lactation. The Neu5Gc content of milk is high in the colostrum (32% of the total sialic acid content of milk) and decreases thereafter until the end of the period considered (6% on day 30). When the Neu5Gc content of gangliosides was evaluated a similar profile to that of Neu5Gc in total sialic acids was found. Gangliosides from colostrum showed the highest Neu5Gc content (21-22% of the total sialic acid content of milk gangliosides). This content dropped towards the end of the period studied (8% on day 90). Our results indicate that a significant supply of Neu5Gc by the milk could be important for the newborn during the first days after parturition.