Effects of dietary vitamin A on growth, feed utilization, lipid metabolism enzyme activities, and fatty acid synthase and hepatic lipase mRNA expression levels in the liver of juvenile orange spotted grouper, Epinephelus coioides

• Published in: Aquaculture Vol. 479; pp. 501 - 507
• Main Authors: Yang, Qihui, Ding, Mingyan, Tan, Beiping, Dong, Xiaohui, Chi, Shuyan, Zhang, Shuang, Liu, Hongyu
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-10-2017
• Subjects: Epinephelus coioides; Growth performance; Lipid metabolism enzyme activities; mRNA expression; Vitamin A; Vitamin A; Epinephelus coioides; Growth performance; Lipid metabolism enzyme activities; mRNA expression
• ISSN: 0044-8486; 1873-5622
• DOI: 10.1016/j.aquaculture.2017.06.024

A 10-week feeding trial was conducted to investigate the effects of dietary vitamin A (VA) on growth, feed utilization, lipid metabolism enzyme activities, and fatty acid synthase (FAS), and hepatic lipase (HL) mRNA expression levels in the liver of juvenile Epinephelus coioides. Six semi-purified diets were formulated to contain VA as retinyl acetate at concentrations of 0, 1000, 2000, 4000, 8000, and 20,000IU·kg−1, providing actual dietary values of 387 (control group), 1256, 2242, 4102, 7635, and 18,231IUVA·kg−1 diet, respectively. A total of 540 juvenile E. coioides were randomly stocked into 18,500L fiberglass tanks with 30 fish per tank and 3 tanks per diet. The results showed weight gain rate (WGR), specific growth rate (SGR), and survival rate (SR), significantly increased in fish supplemented with over 1000IU dietary VA compared with the control group (P<0.05). The feed conversion ratio (FCR) significantly decreased in fish supplemented with dietary VA from 2000IU·kg−1 to 8000IU·kg−1 compared with fish in the other groups (P<0.05). However, supplementing the diet with VA at >8000IU·kg−1 inhibited the growth of juvenile E. coioides (P<0.05). The FAS and HL activities were significantly higher in the livers of the group supplemented with 2000IUVA·kg−1 compared to those of the control group and the group supplemented with 1000IUVA·kg−1 (P<0.05), but dietary VA did not significantly affect whole body lipid deposition in fish (P>0.05). The FAS and HL mRNA expression levels were significantly higher in the groups with dietary VA levels from 4000IU·kg−1 to 8000IU·kg−1 compared to those in the control group (P<0.05). Based on the broken-line regression analysis of WGR and dietary VA levels, the optimal dietary VA requirement is 1775IUVA·kg−1for juvenile grouper. At the same time, under the condition of this experiment, a dietary VA level of 4000IU·kg−1 promoted lipolytic enzyme activity and the expression of lipid decomposition genes in the liver of groupers.
•Dietary VA can significantly improve the growth and lipid metabolism enzyme activities of juvenile E. coioides.•VA can significantly affect the expression of FAS and HL mRNAs in the liver of juvenile E. coioides.•In the present experiment, the optimal dietary VA requirement is 1775IUVA·kg-1 for juvenile E. coioides.