Dietary fish oil replacement by soybean oil: Effect on plasma vitellogenin, sex steroids and ovarian steroidogenesis in Chinese strip-necked turtles (Mauremys sinensis)

• Published in: Aquaculture Research
• Main Authors: Hong, Meiling, Sheng, Cheng, Li, Na, Li, Weihao, Ding, Li, Wang, Dongmei, Shi, Haitao
• Format: Report
• Language: English
• Published: WILEY 2018
• Subjects: Chinese strip-necked turtle; fish oil; soybean oil; steroidogenesis; vitellogenin; GONADOTROPIN-RELEASING-HORMONE; BASS DICENTRARCHUS-LABRAX; TILAPIA OREOCHROMIS-MOSSAMBICUS; TROUT ESTROGEN-RECEPTOR; SALMON SALMO-SALAR; RAINBOW-TROUT; ATLANTIC SALMON; GENE-EXPRESSION; FATTY-ACIDS; ONCORHYNCHUS-MYKISS; Fisheries; Atlantic salmon; Salmo salar
• Online Access: http://ir.imde.ac.cn/handle/131551/23598; https://doi.org/10.1111/are.13775

In order to investigate the effects of dietary fish oil replacement, the turtles (Mauremys sinensis) were fed four experimental diets for 10months: FO (100% fish oil), FSO (70% fish oil and 30% soybean oil), SFO (30% fish oil and 70% soybean oil) and SO (100% soybean oil), sampled at pre-vitellogenesis, vitellogenesis and post-vitellogenesis. The results showed that plasma gonadotropin-releasing hormone (GnRH) levels were the highest at pre-vitellogenesis, which promoted the secretion of gonadotropin and sex steroids. Therefore, plasma luteinizing hormone (LH) and estrogen (E-2) levels were significantly increased at post-vitellogenesis (p<0.05), while follicle-stimulating hormone (FSH) levels increased at vitellogenesis (p<0.05). The FO and FSO groups had significantly higher GnRH and E-2 levels than the other two groups (p<0.05). In addition, plasma vitellogenin (Vtg) levels significantly increased at vitellogenesis and post-vitellogenesis (p<0.05), which were significantly higher in the groups of FO and FSO than SO (p<0.05). Moreover, the expression levels of hepatic estrogen receptor (Er) mRNA were significantly increased at vitellogenesis and post-vitellogenesis while ovarian Cyp191 mRNA were significantly increased at post-vitellogenesis (p<0.05), and both were the lowest in SO. Taken together, the replacement of fish oil with 66.7% soybean oil is feasible.