Transition of milk fatty acid profile and vitamins A and E from colostrum to mature milk in Danish Holstein cows

Abstract

Colostrum, the initial milk produced by mammals after giving birth, has evolved to serve as a primary rich source of essential nutrients for newborns. However, there are considerable changes in nutrient composition from colostrum to mature milk. Colostrum and transition milk have specific fat-soluble vitamin levels, fat level, and fatty acid (FA) composition compared to mature milk, and this unique fatty acid composition of colostrum may reflect the physiological needs of newborn calves. The aim of this study was to investigate changes in the FA profile and levels of vitamins A and E from colostrum to mature milk. Colostrum or milk samples from the 1st (colostrum), 2nd, 3rd, 4th, 5th, 6th, and 13th (as a sample of mature milk) milking were collected from 10 multiparous Danish Holstein cows. The level of vitamin A was significantly affected by milking time (p<0.001), with the highest level in the colostrum (2.3) and the lowest in mature milk (0.5 µg/g). Vitamin E level was significantly affected by milking time (p<0.001), with the highest level in the colostrum (14.8) and the lowest in mature milk (1.8 µg/g). The proportion of C16:0 FA decreased from colostrum to mature milk while the proportion of C18:0 FA increased from the colostrum to mature milk. The proportion of n-6 FA (C18:2n-6, C18:3n-6, C20:3n-6, C20:4n-6, and C22:5n-6) decreased from colostrum to mature milk (p<0.001 for all FA). However, the proportion of C18:3n-3 FA increased from colostrum (3.0) to mature milk (5.9 g/kg of FA; p<0.001), while proportions of C20:5n-3, C22:5n-3, and C22:6n-3 FA decreased from colostrum to mature milk (p<0.001 for all FA). The proportion of trans 18:1n-10 (p=0.005) and trans 18:1n-11 (p<0.001) was affected by milking time and increased from colostrum to mature milk. In conclusion, there is a considerable higher vitamin A and E levels in colostrum compared to mature milk, and vitamin A and E levels were reduced from colostrum to mature milk. Additionally, there were significant changes in the FA profile from colostrum to mature milk, with an increase in C18:3n-3 FA and a decrease in C18:2n-6 FA.