Changes in fatty acid profiles of sea cucumber Apostichopus japonicus (Selenka) induced by terrestrial plants in diets

It has been well known that fatty acid profiles of consumers were flexible in response to the changes in the fatty acid constituents of diets due to the different feed ingredients. No previous studies, however, have been carried out focused on the changes in fatty acid profiles of sea cucumber Apostichopus japonicus (Selenka) induced by the addition of terrestrial plants in diets. In the present study, 4 experimental diets were prepared with gradually increased proportions of terrestrial plants (corn meal and soybean meal) and concurrently decreased proportions of seaweed Sargassum thunbergii. The artificial feed of sea cucumber containing 50% of S. thunbergii was used as the control diet (diet 1), and S. thunbergii were replaced by the mixture of corn meal and soybean meal with the percentages of 10%, 20% and 30% in diets 2, 3 and 4, respectively. Fatty acid profiles of feed ingredients and sea cucumbers fed with the 4 experimental diets were determined. Results showed that fatty acid compositions of sea cucumbers were remarkably affected by those of the diets. Concentrations of fatty acids 16:0, 18:2n-6, 22:6n-3 and ∑n-6 in sea cucumbers appeared to positively correlate with those in the diets. In contrast, contents of fatty acids 20:1n-9, 22:1n-9, 20:3n-3, 20:4n-6 and 20:5n-3 in sea cucumbers showed a significant increase with the increasing levels of corn meal and soybean meal in diets, even though the contents of these fatty acids in corn meal and soybean meal were lower, even absent, compared with S. thunbergii suggesting that sea cucumbers might have the ability to synthesize these fatty acids. Data of the growth performance revealed that sea cucumbers showed the highest weight gain in diet 2 and the lowest weight gain in diet 4 while the growth of the sea cucumbers in diet 3 did not remarkably differ with those in the control group.