Indirect effect of different dietary protein to energy ratio of bait fish mori diets on growth performance, body composition, nitrogen metabolism and relative AMPK & mTOR pathway gene expression of Chinese perch

• Published in: Aquaculture reports 2020-03, Vol.16, p.100276, Article 100276
• Main Authors: Alam, Muhammad Shoaib, Liang, Xu-Fang, Liu, Liwei
• Format: Article
• Language: English
• Subjects: AMPK; Bait fish; Chinese perch; Enzyme activity; Gene expression; mTOR; Protein/energy ratio
• ISSN: 2352-5134; 2352-5134
• DOI: 10.1016/j.aqrep.2020.100276

•The P/E ratio in bait fish diet affected both fish (Bait fish and Chinese perch) growth performance and metabolism.•The Group A fishes (Bait fish and Chinese perch) showed significantly lower growth performance and feed utilization as compared to other groups.•The nitrogen metabolism enzyme activity (ALT, AST, GDH, AMPD) in Group A of Chinese perch were significantly lower than the other groups.•The AMPK-mTOR pathway gene expression in Group A showed low protein synthesis and imbalanced energy homeostasis compared with other groups.•The suitable P/E of bait fish diet in Chinese perch farming can improve fish growth and metabolism with cost-effective aquaculture production. Chinese perch (Siniperca chuatsi) is an important economic freshwater carnivorous fish. Commonly feeds on other live fish or bait fish, and accept an artificial diet only after standard training. The feeding habit of Chinese perch caused high aquaculture costs and consumer prices. However, only a few studies are conducted on Chinese perch live feed (bait fish) or live feed (mori) feeds. Therefore, the present study was conducted to investigate the effect of live feed (mori) and live feed (mori) feeds protein to energy ratio on Chinese perch. Three Iso-energetic diets (16 kJ/g) with graded levels of P/E ratios (19.79, 22.19 and 24.46 mg protein/kJ) each with a protein level of 28.18 %, 31.36 %, and 33.91 % (named A, B, and C) were formulated. Two separate experimental tanks systems were used. In one tanks system, a total of 90 kg live bait fish C. mrigala were distributed into three groups (triplicate tanks (1000 L) for each group) and fed with respective P/E ratio diets. In another tanks system, a total of 270 Chinese perch (30 fish/tank) were divided into three groups (triplicate tanks for each group), distributed into 9 (1000-L) fiberglass tanks and fed with assigned live bait fish at 4 % fish wet body weight, twice a day for 8 weeks. The results showed that P/E ratio in bait fish diets significantly affected bait fish and Chinese perch growth performance, feed utilization, body composition, nitrogen metabolism, protein synthesis, and energy homeostasis. Bait fish in Group A showed significantly lower weight gain (WG), specific growth rate (SGR), and higher Viscerosomatic index (VSI) and Hepatosomatic index (HSI) as compared to other groups. Correspondingly, bait fish in Group A showed significantly low whole-body crude protein and high lipid contents as compared to other groups. Simi