Effects of Dietary Zinc Amino Acid Complex and Zinc Sulfate on Growth Performance, Digestive Enzyme Activity and Immune Response in Asian Seabass (Lates calcarifer)

Abstract

Zinc is an essential trace mineral to fish and vital to various biological processes and function. The artificial diets offered to intensively cultivated fish must possess the zinc content required by the animal metabolism for health maintenance and high weight gain. However, essential elements must also be in an available form to be utilized by the organism. Thus, this study was designed to evaluate the effects of different zinc forms, including organic zinc (zinc amino acid complex) and inorganic zinc (zinc sulfate) as feed additives in diets on in vitro protein digestibility, growth performance, feed utilization, digestive enzyme activity, immune response and muscle quality of Asian seabass (Lates calcarifer). The study was assigned in CRD with 3 treatments and 3 replicates. Three groups of fish with mean weight 22.54 ± 0.80 g, were given a basal diet either unsupplemented (control) or supplemented with 50 mg Zn kg −1 , as zinc sulfate (ZnSO 4) or zinc amino acid complex (ZnAA). The fish were fed experimental diets 3.0% of their body weight per day, twice daily at 08.00 and 16.00 h, for 10 weeks. At the end of the experiment, no significant differences were observed on protein digestibility, survival, growth performance and feed utilization across the three dietary treatments (P>0.05). Fish fed ZnSO 4 diets exhibited a significant increase in the specific activities of total protease, pepsin and trypsin compared with ZnAA and the control (P<0.05). Hematocrit, lysozyme and superoxide dismutase activities of fish fed ZnAA diets were significantly higher compared with all other groups (P<0.05). However, no significant differences were observed for muscle quality and whole body composition (P>0.05). The results of the present work allowed us to conclude that there was no difference in the growth between the two zinc sources but ZnAA supplementation exhibited a higher immunity response in Asian seabass.

Effects of Zinc Status on Expression of Zinc Transporters, Redox-Related Enzymes and Insulin-like Growth Factor in Asian Sea Bass Cells

“…However, in contrast, no differences between the two supplements were observed when total cellular zinc and the expression of MT were analyzed after supplementation for 7 days ( Figure 1 b,c). In agreement with the latter result for SF cells, no differences in final zinc levels after the uptake of ZnAA compared to ZnSO 4 by Asian sea bass where found in vivo [ 3 ]. Several studies indicate that FluoZin3-AM accumulates in certain cellular compartments depending on the cell type and that the probe does not necessarily remain in the cytoplasm [ 24 , 28 , 29 ].…”

“…Asian sea bass ( Lates calcarifer ) is one of the economically most important fish in many countries. It is a popular species for aquaculture, because of its fast growth rate, tolerance to a wide spectrum of environmental conditions, and its high demand in domestic and export markets [ 2 , 3 ]. Thus, efficient aquaculture and research on its optimization resulting in a high yield of healthy fish are of major interest [ 3 , 4 ].…”

“…It is a popular species for aquaculture, because of its fast growth rate, tolerance to a wide spectrum of environmental conditions, and its high demand in domestic and export markets [ 2 , 3 ]. Thus, efficient aquaculture and research on its optimization resulting in a high yield of healthy fish are of major interest [ 3 , 4 ]. In vivo studies on improving culture conditions to maximize output while guaranteeing the health of the fish are ongoing.…”

“…Alternatively, salinity or water flow rates may be adjusted and optimized [ 5 ]. Recently, trace elements were suggested as essential feed additives to optimize the diets for Asian sea bass [ 3 , 6 ].…”

“…Zinc is an essential trace element required by fish, including Asian sea bass [ 3 ]. Zinc promotes growth, amongst others, by altering the expression of growth hormones and factors including insulin-like growth factor (IGF) [ 7 ].…”