Studying the Influence of Copper on the Growth Behavior, Antioxidative Status, and Histology of the Intestine and Liver of Striped Catfish (Pangasianodon hypophthalmus)

Seasonal assessment of selected trace elements in grass carp (Ctenopharyngodon idella) blood and their effects on the biochemistry and oxidative stress markers

Environmental pollution by anthropogenic activity is still a highly relevant global problem. Aquatic animals are a specifically endangered group of organisms due to their continuous direct contact with the contaminated environment. Concentrations of selected trace elements in the grass carp (Ctenopharyngodon idella) (n = 36) blood serum/clot were monitored. Possible effects of the elements on selected biochemical and oxidative markers were evaluated. The concentrations of trace elements (Al, Ba, Be, Bi, Cd, Co, Cr, Cu, Fe, Ga, Mn, Mo, Ni, Pb, Sr, Tl, and Zn) were analysed in the fish blood serum and blood clot by inductively coupled plasma optical emission spectrometry (ICP OES). A general scheme of decreasing concentrations of trace elements in the blood serum samples was: Zn ˃ Fe ˃ Sr ˃ Ba ˃ Ni ˃ Al ˃ Cu ˃ Be ˃ Co; < LOQ (below limit of quantification): Bi, Cd, Cr, Ga, Mn, Mo, Pb, Tl; and in the case of the blood clot, the scheme was as follows: Fe ˃ Zn ˃ Sr ˃ Al ˃ Ni ˃ Ba ˃ Cu ˃ Be ˃ Co ˃ Mn; < LOQ (below limit of quantification): Bi, Cd, Cr, Ga, Mo, Pb, Tl. Significant differences among the seasons were detected. The Spearman R correlation coefficients and linear or non-linear regression were used to evaluate direct relationships between trace elements and selected blood biomarkers. The correlation analysis between biochemical parameters (Na, K, P, Mg, AST, ALT, ALP, GGT, TAG, TP, urea, glucose) and trace elements (Al, Ba, Be, Cu, Fe, Ni, Sr, and Zn) concentrations confirmed statistically significant interactions in both seasons (summer and autumn). The regression analysis between oxidative stress markers (ROS, GPx, creatinine, uric acid, and bilirubin) and elements (Al, Ba, Co, Cu, Fe, Ni, and Sr) content confirmed statistically significant interactions. The results point to numerous connections between the observed elements and the physiological parameters of freshwater fish.

Dietary Copper Requirements for Aquatic Animals: A Review

Copper (Cu) is a vital microelement required for the optimum growth performance and wellbeing of aquatic animals. It contributed to various biological, physiological, and metabolic function in the entire body of the aquatic animals. Further, Cu is a cofactor for several enzymes involved in the antioxidation capacity and metalloenzyme formation. Some ingredients used for aquafeed formulation include sufficient amounts of Cu that can provide aquatic animals with their requirements. Nevertheless, in some cases, external Cu sources are needed to optimize the essential needs of aquatic animals. Inorganic, organic, and nano Cu forms are included in aquafeed and result in regulated physiological and biological functions. The addition of Cu should be added at particular doses considering the species, size, duration, and environmental conditions. Water-borne Cu level should also be considered as long as aquatic animals can obtain their requirements through gills to avoid overdosing and toxicity. Several studies reported the optimum doses of Cu required for optimal growth, productivity, and health status in several aquatic animals. This review article presents the up-to-date results of Cu-related studies in aquafeed. It also helps academia design further studies to better understand the border between Cu requirements and toxicity. Besides, planning for more studies involved in the understanding of the primary mode of action of Cu in aquatic animals' entire bodies.

The Role of Zinc Microelement in Aquaculture: a Review

Trace elements are required in optimum regimes for improving the productivity and wellbeing of aquatic animals. Zinc is one of the main microelements involved in several functions in the animal's body. Zinc potentiates the metabolism function, synthesis of essential enzymes, and the formation of hormones associated with growth, reproduction, immunity, and antioxidative roles in aquatic animals. Several sources of zinc are regularly applied in aquaculture, including inorganic, organic, and nanoparticles. Many studies examined the effects of zinc supplementation in the diets of aquatic animals. The results indicated that zinc could be included in aquafeed in a dose-dependent manner. The effects of zinc depend on the dose, source, duration of feeding, animals' sizes, and experimental conditions. This article comprehensively discusses the results of relevant studies that investigated the effects of zinc on the performances of aquatic animals. The review also intended to update the academia with the previous and current status of using zinc in aquafeed. Furthermore, the article includes up-to-date outputs of relevant studies of using different zinc sources in aquafeed.

Growth Performance, Antioxidative Capacity, and Intestinal Histomorphology of Grey Mullet (Liza ramada)-Fed Dietary Zinc Nanoparticles

Zinc is one of the essential microelements involved in vital physiological and biological functions in the fish body. The study evaluated the growth performance, antioxidative capacity, and intestinal histomorphology of Grey Mullet (Liza ramada)-fed dietary zinc nanoparticles (ZnO-NPs) at 0, 10, 20, and 40 mg/kg for the first time. The final weight and specific growth rate (SGR) of Grey Mullet-fed dietary ZnO-NPs at 20 and 40 mg/kg were meaningfully enhanced (p < 0.05). Further, the weight gain (WG) was significantly higher in fish treated with ZnO-NPs than the control, and fish fed 20-40 mg/kg had the highest WG (p < 0.05). The feed conversion ratio (FCR) was meaningfully reduced in fish fed 20-40 mg ZnO-NPs/kg (p < 0.05). The histomorphology of the intestines revealed a significant improvement in villus height, villus width, and goblet cells by ZnO-NPs. The lysozyme activity, phagocytic activity, and phagocytic index showed higher levels in Grey Mullet-fed dietary ZnO-NPs at 20 mg/kg than fish fed 0, 10, and 40 mg/kg (p < 0.05). Superoxide dismutase (SOD) and catalase (CAT) were markedly improved in Grey Mullet treated with ZnO-NPs compared with the control, and the group of fish treated with 20 mg/kg had the highest SOD and CAT (p < 0.05). Glutathione peroxidase (GPx) was significantly higher in fish fed 20-40 mg/kg ZnO-NPs than fish fed 0-10 mg/kg and fish fed 40 mg ZnO-NPs/kg showing the highest GPx value (p < 0.05). The concentration of malondialdehyde was markedly lowered in Grey Mullet fed ZnO-NPs at varying levels (p < 0.05). Based on the overall results, the regression analysis suggests that ZnO-NPs can be included at 24.61-35.5 mg/kg for the best performances of Grey Mullet.