The present study was undertaken to evaluate the use of roasted coffee powder (RCP; Coffea arabica) in practical diets for common carp, Cyprinus carpio L. to improve their growth, biochemical status, and resistance against Zn toxicity. However, RCP was added to the ingredients of tested diets to represent 0.0 (control), 0.50, 1.0, 2.0, or 5.0 g/kg diet. Fish (10.2 ± 0.42 g) were distributed into various treatments at a rate of 20 fish per 100-L aquarium and fed one of the experimental diets for 10 weeks in triplicates. After the feeding trial, fish from each treatment were further-exposed to 5.0 mg Zn/L for 7 days. It is noticed that final fish performance was not significantly (P < 0.05) affected by increasing RCP levels up to 1.0 g/kg after which fish growth declined. Moreover, fish fed diets containing 2.0–5.0 g RCP/kg consumed less diet than the other treatments giving highest FCRs (1.46 and 1.53, respectively), whereas fish fed 0.0–1.0 RCP/kg diet consumed approximately the same feed amount giving the same FCR (1.30–1.33). Furthermore, energy utilization decreased significantly at 2.0–5.0 g RCP/kg. No significant differences were observed in fish survival and its range was 93.3–96.7% among the different treatments. The supplementation of RCP reduced significantly protein and lipid contents and improved significantly ash content in whole-fish body. Furthermore, RCP inclusion resulted in significant decreases in plasmatic glucose, protein, and lipids, whereas their highest values were obtained with fish fed the control diet. Contrarily, plasmatic AST, ALT, creatinine, and uric acid values increased significantly and nitroblue tetrazolium (NBT) was significantly higher at RCP levels over 1.0 g/kg diet. After Zn exposure, Zn effect was more severe in fish fed RCP-free diet than those fed RCP-enrich diets. In control Zn-exposed fish, plasmatic glucose, total protein, and total lipids were significantly higher; meanwhile, plasmatic AST, ALT, creatinine, and uric acid levels were lower than those in fish fed RCP levels. In addition, NBT decreased due to Zn exposure. Likewise, Zn residues in whole-fish body decreased significantly with increasing RCP levels in diets and lowest daily Zn content was detected in fish fed 2.0–5.0 g RCP/kg diet. These results suggested that RCP supplementation cannot improve fish growth and feed utilization but it could improve their immunity and reduce the impact of water-born Zn toxicity and bioaccumulation in fish body. |
