AUTHOR=Li Shuangfei , Wang Boyu , Liu Liangxu , Song Yingjie , Lv Chuhan , Zhu Xingyu , Luo Yanqing , Cheng Christopher H. K. , Chen Huapu , Yang Xuewei , Li Tao 

TITLE=Enhanced Growth Performance Physiological and Biochemical Indexes of Trachinotus ovatus Fed With Marine Microalgae Aurantiochytrium sp. Rich in n-3 Polyunsaturated Fatty Acids

JOURNAL=Frontiers in Marine Science

VOLUME=7

YEAR=2021

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2020.609837

DOI=10.3389/fmars.2020.609837

ISSN=2296-7745

ABSTRACT=<p><italic>Aurantiochytrium</italic> sp. is a major source of <italic>n</italic>-3 polyunsaturated fatty acids (<italic>n</italic>-3 PUFAs), which are essential nutrients for marine fish. <italic>n</italic>-3 PUFAs have drawn increasing attention because of their great potential for improving the biological functions of fish. The growth performance and immune response of <italic>Trachinotus ovatus</italic> were studied by applying diets with various microalgae content from 1.00 to 11.00% for 8 weeks. The results showed that, with the addition of <italic>Aurantiochytrium</italic> sp., the survival rate, weight gain rate, and specific growth rate of fish increased by a maximum of 1.02, 1.16, and 1.08 times, respectively, indicating that the intake of marine microalgae <italic>Aurantiochytrium</italic> sp. was beneficial for fish growth. As the microalgae content increased, the feed utilization efficiency index feed conversion ratio decreased (maximum 15.00%) and feed efficiency increased (maximum 1.17 times), showing that the addition of <italic>Aurantiochytrium</italic> sp. contributed to the assimilation of fish feed. Furthermore, our results showed that as the addition of <italic>Aurantiochytrium</italic> sp. increased (from 1.00 to 11.00%), the glucose content increased in the blood (from 9.04 to 27.80%). The content of fatty acids ARA, ALA, DHA, and EPA in fish was significantly increased after adding <italic>Aurantiochytrium</italic> sp. in diets. In liver, ARA content increased from 1.17 to 1.63%, ALA increased from 0.56 to 0.85%, DHA increased from 14.44 to 20.61%, and EPA increased from 1.86 to 4.40%. In muscle, ARA content increased from 0.97 to 1.24%, ALA increased from 0.59 to 0.81%, DHA increased from 14.63 to 14.82%, and EPA increased from 4.58 to 5.19%. Positive changes were observed in the blood cell count of immune related cells (white blood cells, lymphocytes, monocytes, neutrophils, and red blood cells). These results indicated that microalgae rich in <italic>n</italic>-3 PUFAs could increase the number of immune cells, thus helping to improve fish immunity and disease resistance.</p>