SEASONAL-VARIATIONS IN THE CONCENTRATION OF GANGLIOSIDES AND SIALIC ACIDS IN MILK FROM DIFFERENT MAMMALIAN-SPECIES

Seasonal changes in the ganglioside content of cows', goats' and ewes' milk were studied over a one year period. All species considered show ed the highest ganglioside content in autumn. The minimum ganglioside content was observed in summer milk for cows and goals but not for ewe s. A correlation between the fat and ganglioside content of milk seems to emerge from these and other results. Identified (selected for milk production) Holstein-Friesian cows had a lower ganglioside content th an unidentified cows (milk samples from bulk tanks of a dairy factory) . Minor changes in the ganglioside pattern of cows' milk were detected . However, seasonal variations in the total sialic acid content of cow s' and goats' milk through the year were not detected. The availabilit y of lipid precursors rather than the sialic acid content or sialyltra nsferases activity seems to be the limiting factor for milk gangliosid e biosynthesis. Finally, the ganglioside content of cows' milk was not affected by mild heat-treatment (thermization, 65 degrees C, 30 s).