Comparison of the lipid composition of three adipose tissue types of male and female wild nile crocodiles (Crocodylus niloticus)

Abstract

We describe and compare the fatty acid composition of three different adipose tissue types, namely, abdominal, tail, and steatotheca (an abdominal fat body) tissues of healthy wild Nile Crocodiles (Crocodylus niloticus). No significant differences were observed in the fatty acid composition among the three fat tissues, apart from eicosapentaenoic acid, which occurs in small amounts of less than 1% in all the types of tissue. In individual animals, limited variation in the steatotheca may occur compared with the other two adipose fats. The total fat of the male crocodile is more saturated, with 44.4% ± 3.2% saturated fatty acids compared with the 42.0% ± 3.2% of the female. The greatest differences between the sexes were observed for pentadecylic, margaric, stearic, palmitoleic, vaccenic, and oleic acids. No interaction between gender and anatomical position of fatty acids was observed. This is a first comparative study of fat composition of different adipose tissues in a reptile. When the data are compared with similar data of fish, birds, and mammals, it may be concluded that differentiation of the composition of adipose fat is an evolutionary development of mammals.