Quantifying the dietary potassium requirement of subadult grass carp (Ctenopharyngodon idellus) |
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Authors: | C. Chen W. Zhu F. Wu M. Liu Q. Tan D. Han S. Xie X. Liang |
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Affiliation: | 1. Fisheries College, Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture of China, Huazhong Agricultural University, Wuhan, China;2. State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China |
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Abstract: | A growth trial lasting for 12 weeks was conducted in 21 net cages to determine the dietary potassium (K) requirement of subadult grass carp (Ctenopharyngodon idellus) (Average weight: 331.3 g). Seven isonitrogenous and isoenergetic semi‐purified diets were compounded with different dietary K level. The specific growth rate (SGR) of fish was significantly (P < 0.05) improved by dietary K supplementation, SGR and the gill Na+‐K+ ATPase activity increased first and then decreased (P < 0.05) as dietary K level increased. The highest SGR and gill Na+‐K+ ATPase activity values were both observed at 6.38 g kg?1 group. Dietary K level showed significant (P < 0.05) effect on serum superoxide dismutase (SOD) and glucose (GLU), the maximum values of SOD and GLU were in 8.42 and 6.38 g kg?1 group, respectively. The body lipid content of the 6.38 g kg?1 group was significantly (P < 0.05) lower than that of the control. However, the ash content in the 8.42 g kg?1 group was significantly higher than those in the 1.21, 2.21, 4.41 and 6.38 g kg?1 group. When dietary protein was 320 g kg?1 and the waterborne potassium ranged from 6.86 to 9.10 mg L?1, the dietary K requirement for subadult grass carp judged from SGR and gill Na+‐K+ ATPase activity is 5.38 and 7.41 g kg?1 diet, respectively. |
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Keywords: | blood biochemicals body composition grass carp growth performance Na+‐K+ ATPase potassium |
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