Dietary potassium requirement of juvenile grass carp (Ctenopharyngodon idella Val.) based on growth and tissue potassium content

Authors

  • Jian-jun Liang,

    1. Nutrition Laboratory, Institute of Aquatic Economic Animals, School of Life Science, Sun Yat-Sen University, Guangzhou, China
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  • Hui-jun Yang,

    Corresponding author
    1. Nutrition Laboratory, Institute of Aquatic Economic Animals, School of Life Science, Sun Yat-Sen University, Guangzhou, China
    • Correspondence: H-J Yang, Institute of Aquatic Economic Animals, School of Life Science, Sun Yat-sen University, 135 Xin'gang Xi Road, Guangzhou 510275, China. E-mail: edls@mail.sysu.edu.cn

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  • Yong-jian Liu,

    1. Nutrition Laboratory, Institute of Aquatic Economic Animals, School of Life Science, Sun Yat-Sen University, Guangzhou, China
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  • Li-Xia Tian

    1. Nutrition Laboratory, Institute of Aquatic Economic Animals, School of Life Science, Sun Yat-Sen University, Guangzhou, China
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Abstract

A growth trial was conducted to estimate the optimum concentration of dietary potassium (K) for grass carp (Ctenopharyngodon idella). Triplicate groups of grass carp (3.96 ± 0.06 g) were fed diets containing graded levels (0.87, 2.90, 5.37, 7.54, 9.87 and 12.4 g kg−1) of K for 8 weeks. Final body weight, weight gain and feed efficiency and gill Na+-K+ ATPase activity were highest in fish fed with 9.87 g kg−1 dietary K and lowest in fish fed the basal diet (P < 0.05). The K contents in whole body and muscle were linearly increased up to the 9.87 g kg−1 dietary K and then levelled off beyond this level, whereas in scales and vertebrae up to the 7.54 g kg−1 dietary K (P < 0.05). However, dietary K levels had no significant effect on ash, Ca, P and Mg contents in whole body, scales, vertebrae or muscle. Analysis using polynomial regression of weight gain and gill Na+-K+ ATPase activity and using the broken-line regression of whole body K concentrations indicated that the adequate dietary K concentration for grass carp is about 9.45–9.99 g kg−1 diet.

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