Vitamin A status in the grey seal (Halichoerus grypus) on Sable Island

Vitamin A and beta-carotene concentrations in serum, liver and blubber fat were investigated in 65 grey seals of different age and sex in the pupping colony on Sable Island, Canada to determine the vitamin A status. In none of the investigated samples could beta-carotene be detected. There were no differences in the concentration of vitamin A in serum, liver and blubber between male (213 micrograms/l, 376 micrograms/g, 22 micrograms/g respectively) and female (205 micrograms/l, 319 micrograms/g, 19 micrograms/g respectively) juveniles. In adult males concentrations of vitamin A in serum, liver and blubber were higher (260 micrograms/l, 503 micrograms/g, 34 micrograms/g respectively) than in juveniles indicating an age dependent increase of vitamin A in liver and blubber. Contrary to this in lactating females concentrations of vitamin A in serum, liver and blubber were significantly different than in the other animals. While the level of vitamin A in serum and blubber was two times higher with 413 micrograms/1 and 62 micrograms/g respectively, the concentration of vitamin A in liver was much lower (265 micrograms/g) compared to juveniles and adult males. It is possible that the intensified lipid metabolism during lactation, necessary to match the energy requirements of the rapidly growing pup, causes these extreme differences in vitamin A concentrations in serum, liver and blubber of lactating females compared to juveniles and adult males. Due to high concentration of vitamin A in blubber and the high proportion in blubber to total body weight, the blubber represents approximately 40% of total body reserves of vitamin A.