Effects of waterborne cadmium exposure on growth performance, specific dynamic action, and energy budget of southern catfish Silurus meridionalis

This study investigated the effect of waterborne cadmium (Cd) exposure on the growth performance, specific dynamic action (SDA), and energy budget of southern catfish ( Silurus meridionalis ). S. meridionalis was exposed to various Cd concentrations (0–500 μg L −1 ) for 8 weeks. The specific growth rate (SGR), apparent digestibility, protein apparent digestibility, SDA parameters, and components of energy budgets were then determined. Compared to the control group, SGR was significantly reduced upon Cd exposure at 250 μg L −1 and 500 μg L −1 . Compared to the control group, the experimental groups (62.5–500 μg L −1 ) showed significantly lower total feed intake and feed conversion efficiency. The apparent digestibility and protein apparent digestibility was significantly decreased in the 250 μg L −1 and 500 μg L −1 experimental groups compared to the control group. A significantly lower peak metabolic rate, SDA, and SDA coefficient were observed in the 250 μg L −1 and 500 μg L −1 experiment groups compared to the control group. The ratio of growth energy to assimilation energy in the 62.5–500 μg L −1 experimental groups was significantly lower than that of the control group. There was a significant increase in the ratio of metabolic energy to assimilation energy in Cd exposed groups compared to the control group. These results indicate that waterborne Cd exposure decreased the protein apparent digestibility, resulting in decreased SDA and SDA coefficient. Waterborne Cd exposure resulted in increased proportion of excretion energy and feces energy in S. meridionalis , whereas assimilation energy was reduced. Moreover, for assimilation energy, the energetic proportion for metabolism was increased, whereas the energetic proportion for growth was reduced