Effects of different protein levels on Pacific white shrimp (Penaeus vannamei Boone, 1931) farming in a system with limited water exchange

Limited water exchange system is an environmentally friendly system that pursues the goals of sustainable aquaculture and is used in modern aquaculture. In the present study, the effect of different levels of dietary protein on water quality, growth performance and biochemical composition of microbial mass in the system with limited water exchange was investigated. Western white shrimp juveniles with an average weight of 2.5 g were studied in fiberglass tanks with a volume of 160 liters and a density of 1 fish per liter for 5 weeks. Four experimental treatments with different levels of dietary protein including 40, 36, 33 and 30% were considered in the system with limited water exchange. The results of the present study showed that the amounts of dissolved oxygen, pH, total ammonia nitrogen (1.11 mg/l) are higher in the treatment of diet with 40% protein. Growth performance in 33% and 36% protein showed a significant difference compared to 30% and 40% level of protein (P <0.05), so that higher values were observed in 33% and 36% protein treatments. The biochemical composition of the microbial mass was affected by different dietary proteins (P <0.05) and higher amounts of lipid (2.17%) and ash (35.44% of dry weight) were observed in the treatment with 30% protein. According to the present study, it was found that different dietary proteins affect water quality, growth performance of western white shrimp and microbial mass composition and the optimal values in the diet are 33% and 36% of protein.