A study on growth parameters, blood factors and proximate composition of rainbow trout (Oncorhynchus mykiss) cultured in underground brackish and freshwater

In this research, growth rate, blood parameters and proximate composition of rainbow trout (Oncorhynchus mykiss) cultured in brackish and freshwater were evaluated. Two treatments (brackish and freshwater) in ۳ replications were investigated. Six ۱.۵ m³ fiberglass tanks were used for this experiment, containing ۱۸۰ rainbow trout specimens with average weight of ۴۷.۲±۰.۱g. Feeding rate in treatments was about ۳% of body weight based on water temperature and fish biomass. Total length and weight of fish were measured in ۱۵ days intervals. After ۱۳۵ days of culture period, some fish samples were transferred to the Lab. Blood were directly collected from the heart. Muscle composition was analyzed for proximate composition. The results showed that the body weight of samples in brackish water was increased significantly after ۴۵ days of culture period. Blood factors including WBC, RBC, Hb, Hct, MCV, MCH, MCHC, lymphocyte, thrombocyte and concentration of K+ ions in fish cultured in brackish water showed a significant increase (P<۰.۰۵). Muscle composition analysis showed a significant increasing (p<۰.۰۵) in fat and dry matter in freshwater treatment, while moisture was significantly higher in brackish water (P<۰.۰۱)

Keywords:

Rainbow trout , brackish water , freshwater , blood factors , proximate composition , growth