Exogenous supplementation of papain as growth promoter in diet of fingerlings of Cyprinus carpio

The effect of different levels of papain (1%, 2% and 4%) supplemented feed in Cyprinus carpio on growth rate, nutrient digestibility, gross protein retention (GPR), feed conversion ratio (FCR), protein efficiency ratio (PER), apparent net protein utilization (ANPU), energy conversion efficiency (ECE%) and nitrogen retention efficiency (NRE) was studied. The fish fed on the feed supplemented with 2% papain treatment resulted in lowest feed conversion ratio (FCR), better growth rate, high protein digestibility, higher protein efficiency ratio (PER), good gross energy retention, better apparent net protein utilization (ANPU), energy conversion efficiency ECE (%) and nitrogen retention efficiency (NRE). All these parameters were lowest in case of control (P > 0.05). Maximum growth rate, nutrient digestibility, gross protein retention (GPR), feed conversion ratio (FCR), protein efficiency ratio (PER), apparent net protein utilization (ANPU), energy conversion efficiency (ECE %) and nitrogen retention efficiency (NRE) were seen during the 8th week of the study period and 2% papain level showed best results (P < 0.05). The physicochemical parameters were within the optimum range as desired for fish culture practices. Papain did not affect the water quality parameters and had no adverse effect on feeding response of fish. Thus, supplementation of papain to feed of common carp at a level of 2% resulted in better growth performance.