Vitamin E status and the dynamics of its transfer between mother and pup during lactation in grey seals (Halichoerus grypus)

Concentrations of vitamin E, a powerful antioxidant, were measured in milk and serum of 18 grey seal (Halichoerus grypus) mothers and in the serum of their pups sampled up to 6 times between parturition and weaning on the Isle of May, Scotland, in 1998 and 2000. The vitamin E concentration in colostrum (89.4 +/- 22.5 mg/kg milk; mean +/- SD) was 4.5 times greater than that in later milk (20.9 +/- 5.0 mg/kg milk). It then remained constant until the end of lactation. The decline in concentration of vitamin E in grey seal milk corresponded to a drop in the vitamin E concentration in mothers' serum between parturition (14.0 +/- 4.8 mg/L serum) and the second half of the lactation period during which the serum vitamin E concentration remained stable (9.6 +/- 3.2 mg/L serum). Circulating vitamin E concentrations varied significantly among mothers but there was no relationship with mother's age. Despite these differences between mothers, individuals produced milk with very similar vitamin E concentrations. The vitamin E concentration in grey seal pups' serum was low at birth (lowest concentration 3.1 mg/L serum) but increased sharply to a peak around days 1-3 (31.2 +/- 5.2 mg/L serum). It then fell, before stabilizing until the end of lactation (21.1 +/- 4.5 mg/L serum), reflecting the changes reported in the milk.