Effects Of Ration Level And Temperature On Growth,Faecal Production, Nitrogenous Excretion And Nitrogen Budget Of Juvenile Siniperca Chuatsi (Basilewsky)

Mandarin fish (Siniperca chuatsi (Basilewsky)) belongs to Perciformes, Percoidei, Percichthyidae, Siniperca. Because of its fast growth, meat delicate, delicious and nutrient-rich, mandarin fish is a rare and precious economic species of freshwater fish with a long standing reputation.In this paper, we studied the effect of ration level and temperature on body composition, growth, faecal production, nitrogenous excretion and nitrogen budget of juvenile mandarin fish with the method of bioenergetics, in order to reveal the regularity of growth, faecal production, nitrogenous excretion of juvenile mandarin fish under the condition of different feed quantity and temperature, and to supply theoretical basis for an economical and healthful model of farming method of juvenile mandarin fish. The results of this study are summarized as follow.1. Effect of ration level on body composition, growth, faecal production, nitrogenous excretion and nitrogen budget of juvenile mandarin fishBody composition, growth, faecal production, nitrogenous excretion and nitrogen budget of juvenile mandarin fish (initial body weight2.52-3.79g, average3.11g) at various ration levels (starvation,1%,2%,3%,4%of initial body weight per d ay, and satiation) were investigated in this study. The relationships between growth, nitrogenous excretion as well as faecal production and ration were established. W ater temperature was controlled between26.5℃to28℃, and the average level was27.3℃.The results showed that as ration level increased, a positive correlatio n was observed for the contents of dry matter, protein and lipid, and a negative c orrelation for ash content. As the increase of ration level, food conversion efficien cy (FCE,%) tended to increase, feed absorption efficiency (FAE,%) tended to in crease within a narrow range and specific growth rate increased with a linear patt ern. Excretion nitrogen [UN, mg/(g-d)] and faecal nitrogen [FN, mg/(g·d)] increased markedly with increased ration level (RL,%per day), described as UN=0.4496R L+0.0979for nitrogenous excretion and FN=0.0781RL+0.0192for faecal nitroge n, respectively. As ration level increased, allocation of nitrogen to growth increase d with the decrease in proportions of excretion nitrogen and faecal nitrogen, the ni trogen budget of juvenile mandarin fish at satiation was:100CN=45.20GN+7.46FN+47.34UN.2. Effect of temperature on growth, faecal production, nitrogenous excretion and nitrogen budget of juvenile mandarin fishThree temperature groups(22℃,26℃,30℃) have been designed in this study, and the initial body weight of mandarin fish was13.47±1.72g. In this study, we have investigated the effect of temperature on body composition, growth, faecal production, nitrogenous excretion and nitrogen budget of juvenile mandarin fish, and have established the relationships between dry matter, protein and body weight as well as relationships between maximum ration level, specific growth rate, food nitrogen, growth nitrogen, faeces nitrogen, excretion nitrogen, nitrogen budget and temperature. The results showed that as temperature increased, a positive correlation was observed for the maximum ration level(RL,%/d), body weight, specific growth rate(SGR,%/d), feed absorption efficiency (FAE,%) and contents of dry matter and protein, but a negative correlation for food conversion efficiency (FCE,%) and the protein content of feaces. Food nitrogen, growth nitrogen and excretion nitrogen increased whereas faeces nitrogen decreased with increased temperature. As temperature increased, allocation of nitrogen to growth and faecal decreased with the increase in proportions of excretion nitrogen, markedly. The relationship between maximum ration level of weight matter (RLw,%/d), food nitrogen(CN, mg/(g-d)), excretion nitrogen(UN, mg/(g-d)) and temperature(T,℃) could be described as follow:RLw=10.8791nT-20.57, CN=13.8351nT-26.16, UN=10.7281nT-25.449. Nitrogen budgets of juvenile mandarin fish at different temperature(22℃,26℃,30℃) were100GN=45.82CN+4.38FN+46.29UN,100GN=43.72CN+3.45FN+50.38UN,100GN=42.94CN+2.67FN+52.83UN.