GROWTH PERFORMANCE AND BIOCHEMICAL CHANGES IN COMMON CARP, CYPRINUS CARPIO L. EXPOSED TO WATER-BORN ZINC TOXICITY FOR DIFFERENT PERIODS
Mohsen Abdel-Tawwab1,
Mohamed N.M. Mosaad2 and Nahla E.M. Ismaiel1
1Department of Fish Biology and Ecology, Central Laboratory for Aquaculture Research, Agriculture Research Center, Ministry of Agriculture, Egypt.
2Zoology Department, Faculty of Science, Benha University, Benha, Egypt.
Received 8/ 1/ 2013 Accepted 19/ 2/ 2013
Abstract
The present study was carried out to investigate the effect of sublethal zinc (Zn) concentrations on the growth, biochemical variables, and Zn residues in common carp, Cyprinus carpio L.. This study was based on a bifactorial design with three levels of Zn concentrations (0.0, 5.0 and 10.0 mg/L) and four exposure periods (7, 14, 28, and 56 days). Fish (18.1 – 19.1 g) were exposed to 0.0 (control), 5.0 and 10.0 mg Zn/L for 7, 14, 28, and 56 days. At each time interval and each treatment, fish were collected, weighed and sampled to measure the growth and biochemical variables. Also, Zn residues in whole-fish body were determined. Growth performance was significantly reduced with increasing Zn concentrations. However, the fish (26.4 g) exposed to 10.0 mg Zn/L for 56 days grew lower than that of the control group (38.5 g). Likewise, the optimum feed intake and feed conversion ratio were obtained at control group (28.7 g feed/fish and 1.43, respectively) at 56 days. Furthermore, glucose, AST, ALT, creatinine, and cortisol increased significantly with increasing Zn concentration and exposure time, with maximal values of glucose, AST, ALT, uric acid, and creatinine observed in the 10.0 mg Zn/L treatment after 56 days (1.27 g/L, 82.0 IU/L, 27.0 IU/L, 39.0 mg/L, and 9.4 mg/L, respectively). Meanwhile, the highest values of serum protein and lipids of (23.7 and 12.3 g/L, respectively) were obtained in the control fish reared for 56 days, whereas the lowest values were observed in fish exposed to 10.0 mg Zn/L for 56 days (11.0 and 6.2 g/L, respectively). The content of whole-body moisture and total ash increased significantly, while crude protein and total lipid contents decreased significantly with increasing Zn concentrations. In addition, Zn exposure increased the Zn residues in fish body; however, Zn bioaccumulation in fish body was Zn dose and time dependant. The present study revealed that the growth and health status of common carp were deteriorated by Zn toxicity.
Key words: common carp, water-born zinc, zinc toxicity, exposure periods, biochemical changes.
