The eco-nutrition requirements for dietary protein and its rhomb characteristics in juvenile turbot (Scophthalmus maximus L.) |
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| Authors: | Yong Li Keyong Jiang Guoxiang Sun Tingting Gao Bangwei Zhou |
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| Institution: | LI Yong **,JIANG Keyong,SUN Guoxiang,GAO Tingting,ZHOU Bangwei Institute of Oceanology,Chinese Academy of Sciences,Qingdao 266071,China |
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| Abstract: | We evaluated the dietary protein requirements of juvenile turbot (Scophthalmus maximus L.) and their effects on aquatic quality. Five experimental diets were formulated containing 450, 480, 500, 520, and 540
g/kg. Each diet was randomly assigned to triplicate groups of juvenile turbot (mean initial body weight 34.5 ± 5.5 g) for
88 d. Both the weight gain ratio and feed efficiency increased with increasing dietary protein up to 500 g/kg, but no further
improvement was detected when dietary protein levels were >500 g/kg. Protein intake and digestion increased with protein levels,
while fecal nitrogen and nitrogen content in seawater increased only when dietary protein exceeded 500 g/kg. Protein digestibility
was highest at intermediate dietary protein levels. Chemical oxygen demand, nitrite-nitrogen (NO2?-N) and phosphatic-phosphor (PO43?-P) levels increased in the rearing water as dietary protein levels increased. The optimum eco-nutrition level of dietary
protein for juvenile turbot was 500 g/kg under the current experimental conditions. The diets containing 540 and 500 g/kg
protein had similar growth rates and feed conversion ratios, but levels of ammonia (NH4+) and nitrogen were considerably higher in the water and feces, respectively, at the higher level of dietary protein. The
difference in the pattern of change between body weight gain and ammonia concentration in water with increasing dietary protein
is described by rhomb characteristics. |
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| Keywords: | eco-nutrition requirement rhomb characteristics protein aquatic quality digestion turbot |
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