Optimal Macronutrient Composition Of Formulated Diets For David’s Schizothoracin (Schizothorax (Racoma)Davidi) Juveniles

A three component mixture design (Cornell Design) was used to investigate the optimal composition of macronutrients for David’s schizothoracin(Schizothorax (Racoma) davidi) juveniles (2.0±0.1g initial weight). Protein, lipid and carbohydrate were varied between33-51%,3-18%and23-32%dry wt., respectively. Of the21diets,20diets were fed to fish in20groups (each group three replicate nets) randomly, and1centre diet was fed to fish in four replicate nets to estimate inter-net variation in an indoor cement pit with a tiny running water system randomly.1920test fish were divided into64nets and there were30test fish in each net. The experiment lasted for60days. The test results showed that the dietary macronutrient composition was not reflected in the survival rate of the fish significantly except for significant decline at33%dietary protein (P<0.05). There was a positive effect of increasing dietary protein levels up until45%on the growth, while33%-39%dietary protein resulted in growth depression significantly (P<0.05). Beside12% dietary lipid, the fish at9%dietary lipid showed significantly better growth than other dietary lipid levels (P<0.05). The lipid contents in fish body or liver increased significantly (P>0.05), and fatty degeneration in hepatocytes was obvious as dietary lipid level was=15%. The dietary carbohydrate composition was not reflected in the growth of the fish significantly (P>0.05), but32%dietary carbohydrate level strongly increased accumulation of carbohydrate in whole baby and the liver of the fish (P<0.05). It could be concluded that the optimal protein requirement appears to be45%, based on the limits of9%for lipids and27%for carbohydrate in the diets, while the dietary general energy (GE) and protein energy rate (P/E) are20.0MJ/kg and25g/kJ for David’s schizothoracin juveniles.