Effect of Salinity on Feed Conversion Rate, Feed Conversion Efficiency, Protein Intake and Efficiency of Protein Utilization Ratio in Common Carp Cyprinus Carpio

This study was conducted to investigate the impact of increased salinity on some growth parameters of common carp ( Cyprinus carpio). Fish, gradually have been exposed to the salt concentrations of 5, 10 and 15g/L, as well as tap water (control treatment of 0.1 g/L) for 84 days divided on 12 weeks, and each of salt concentration represented independent treatment with two replications. 80 fish at average weight of 15 ± 3 g were randomly distributed on 8 glass tanks at 10 fish / tank to study the effect of salinity on feed conversion rate, feed conversion efficiency, protein intake and efficiency of protein utilization ratio in common carp. Results showed a decrease in feed conversion rate to16.59, 24.49 and -20.11, when the salinity increased to 5, 10 and 15 g/L respectively, compared to the control treatment (13.32). This is reflected on feed conversion efficiency, which slump to 6.02, 4.08 and - 4.97% in the salt concentrations of 5, 10 and 15 g/L respectively, compared to the control treatment (7.50%). Protein intake, also decreased to 25.23, 24.07 and 21.37% with the increasing of salinity to 5, 10 and 15 g/L respectively, compared to the control treatment (25.67%), while the efficiency of protein utilization slump to 21.32, 10.94 and -10.07% in the salt concentrations of 5, 10 and 15 g/L, respectively while it was 29.16% in the control treatment. Fish were fed on a commercial diet with a protein content of 31% during the experiment.