Milk composition, fatty acids profile and fat globule size of bottlenose dolphin (Tursiops truncatus, Montagu 1821) milk at early lactation

Abstract

Research data on milk composition in cetaceans are scattered and fragmentary. This paper analyses the gross and mineral composition, the fatty acids profile and the fat globule size of bottlenose dolphin ( Tursiops truncatus ) colostrum and milk at early lactation. The milk samplings were carried out on three lactating female of bottlenose dolphins at the 1st, 4-5 and 20-42 day post partum. High percentages of dry matter (51.88%), fat (26.08%) and protein (13.83%) were found in the colostrum on the first day, while there was a tendency for these components to decrease in the milk. The average diameter the milk fat globule (7.07 um) of this species was assessed for the first time. The milk was rich in unsaturated fatty acids, which were more than twice compared to the saturated fatty acids (unsaturated / saturated ratio = 2.6). The main fatty acids of dolphin milk were C16: 0, C18: 1 n-9, C20: 1 n-11, C20: 5, C22: 6 n6. Furthermore C12: 0 showed double contents in milk compared to colostrum, while C20: 1 n9 and C20: 1 n7 were respectively five and three times higher in milk than colostrum. Finally, C18: 3 n3 was approximately 4 times lower in milk than in colostrum while C24: 0 and C24: 1 tended to halve. The changes found in the fatty acid profile could be linked to the animals' energy metabolism and lipomobilization during lactation. This study contributes to improve scientific knowledge on dolphin milk composition and nutrient supply in dolphin calves.

Health Status of Stranded Common Bottlenose Dolphins (Tursiops truncatus) and Contamination by Immunotoxic Pollutants: A Threat to the Pelagos Sanctuary—Western Mediterranean Sea

“…However, the transfer of contaminants is particularly effective during lactation as the milk of these marine mammals is very rich in lipids dispersed in the form of droplets (milk fat globules) and packed into a membrane inherited from the mammary gland [116]. In a recent study [117], it was found that in bottlenose dolphin milk there is an average of 20.57% of lipids; the study also highlighted the abundance of unsaturated fatty acids (Unsaturated Fatty Acids/Saturated Fatty Acids ratio = 2.64). However, it should not be forgotten that the composition of fatty acids in milk is linked to food intake and mobilization from fat (blubber) deposits [118].…”