Open AccessDietary Protein Level Affects the Growth Performance of Large Male Genetically Improved Farmed Tilapia, Oreochromis niloticus , Reared in Fertilized Freshwater Cages
Author(s) -
Liu Wei,
Jiang Ming,
Wu JinPing,
Wu Fan,
Tian Juan,
Yang ChangGeng,
Wen Hua
Publication year - 2017
Publication title -
journal of the world aquaculture society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.655
H-Index - 60
eISSN - 1749-7345
pISSN - 0893-8849
DOI - 10.1111/jwas.12384
Subject(s) - biology , oreochromis , zoology , transaminase , tilapia , protein efficiency ratio , feed conversion ratio , triglyceride , dietary protein , nile tilapia , body weight , cholesterol , fish <actinopterygii> , endocrinology , biochemistry , fishery , enzyme
An 8‐wk experiment was conducted to evaluate the effects of dietary protein on the growth performance, body composition, and serum biochemical indices of large male genetically improved farmed tilapia ( GIFT ), Oreochromis niloticus , reared in fertilized freshwater cages. Six semi‐purified diets were formulated, containing 18.05, 22.39, 25.97, 31.62, 35.97, and 39.89% protein (designated as P18 , P22 , P26 , P30 , P34 , and P38 , respectively). Each diet was fed to randomly selected fish (initial mean weight 216.7 g) in four cages. At the end of the experiment, the final body weights varied significantly ( P < 0.05), ranging from 520 to 580 g. Fish receiving the P30 diet had the highest final weight value (580.5 ± 5.4 g). Weight gains of fish fed the P26 and P30 diets were significantly higher ( P < 0.05) than those fed the P18 and P38 diets. The apparent feed efficiency of fish fed the P18 diet was significantly lower ( P < 0.05) than that of fish in the other groups except the P22 group ( P > 0.05). The apparent protein efficiency ratio decreased gradually with increasing dietary protein. Whole‐body moisture and ash showed no significant difference ( P > 0.05), but protein and fat content were significantly affected by dietary protein level ( P < 0.05). No significant differences were found for serum total protein, triglyceride, total cholesterol, glutamic‐oxaloacetic transaminase, and glutamic‐pyruvic transaminase levels among different diets ( P > 0.05); only serum glucose level was affected by dietary protein levels ( P < 0.05). Second‐order polynomial regression of weight gain suggested 29.3% dietary protein is adequate content for maximum growth of large male GIFT , O. niloticus .