Growth performance and body composition of kutum fingerlings, Rutilus frisii kutum (Kamenskii 1901), in response to dietary protein levels

A feeding trial was conducted to determine the optimal dietary crude protein requirement for Rutilus frisii kutum fingerlings. Five isoenergetic experimental diets were formulated to contain graded levels of protein (32%, 37%, 42%, 47%, and 52%). Triplicate groups of 80 kutum (average weight 0.5 g) were stocked in 250-L tanks and fed to apparent satiation 3 times a day for 8 weeks. The results indicate that the growth performance and feed utilization of kutum were significantly (P < 0.05) affected by dietary protein level. The second polynomial regression of weight gain against protein level yielded an estimated optimal dietary protein requirement of 41.6%. Weight gain, specific growth rate, and feed efficiency increased with increasing the dietary protein level from 32% to 42%, but decreased significantly (P < 0.05) with further increases in dietary protein. The protein efficiency ratio was inversely correlated with dietary protein level. Feed intake was not affected (P > 0.05) by dietary protein level. No significant difference was found in the whole-body protein, lipid, moisture, or ash contents of fish fed the different dietary protein levels. The results obtained from this study could be beneficial in order to formulate artificial feed for aquaculture of kutum fingerlings.