Effects of chronic exposure of cadmium on growth performance, bioaccumulation and hematological parameters of genetically improved farmed tilapia

This study was conducted to evaluate the chronic exposure of cadmium on growth performance, bioaccumulation, and hematological parameters of genetically improved farmed tilapia (GIFT). Two concentrations of cadmium (50 μgL^-1 and 100 μgL^-1) with control were used. Twelve fish with an initial mean weight of 12.84 ± 0.53 g were randomly assigned quadruplicated treatments (total 144 fish) and the experiment lasted for six weeks. In the end, growth performance and feed utilization efficiencies were assessed by using % specific growth rate (%SGR), % average daily gain (%ADG) and feed conversion ratio. The pattern of Cd accumulation in different tissues and hematological parameters were examined. Mean body weight, %ADG, %SGR, hematocrit and packed cell volume were not affected by the treatments. A significantly higher survival rate (100 %) was observed in control followed by CD50 (87.50 %) and CD100 (78.13 %). The rate of Cd accumulation in various tissues was in the order of liver > gills > muscle > skin in each treatment. Among tested concentrations, the highest accumulation was observed in CD100 for each tissue. Both red blood and white blood cell count (2.21 ± 0.07 × 106 mm^-3 and 468.00 ± 6.61 × 103 mm^-3 respectively) were significantly higher in control and it was lowest in CD 100 (1.28 ± 0.04 × 106 mm^-3 and 205.19 ± 8.94 × 103 mm^-3). The results of this study supported the conclusion that there is a significant effect of the chronic exposure to cadmium on the bioaccumulation and hematological parameters of the GIFT tilapia even at the ecologically relevant concentration.