Dietary conjugated linoleic acid (CLA) and lecithin affects levels of serum cholesterol, triglyceride, lipoprotein and hypoxic stress resistance in rainbow trout (Oncorhynchus mykiss)

Considering the role of conjugated linoleic acid (CLA) and soybean lecithin (SBL) in fat digestion, absorption and metabolism as well as stress resistance in aquatic organisms, the current study was a 74-day attempt to investigate the synergistic effects of these two compounds on stress resistance and blood lipoprotein levels of rainbow trout (Oncorhynchus mykiss) weighing 120±5 g. Nine isonitrogenous and isocaloric experimental diets containing 1, 2 and 3% CLA and 2, 3 and 4% soybean lecithin on the basis of the basal control diet (free from CLA and lecithin) were formulated. The fish were exposed to three ascending periods of hypoxic stress (7.5, 15 and 30 min) at the end of culture period. The dissolved oxygen was decreased to 1.96 ppm by injecting nitrogen gas. Significantly higher levels of cortisol and glucose were detected in fish fed on diets having higher levels of SBL (2%) and CLA (3%) at higher stress time improving the resistance to hypoxia stress (P≤0.05). Moreover, levels of triglyceride (TRG), cholesterol (COL), low density lipoprotein (LDL), very low-density lipoprotein (VLDL) and high density lipoprotein (HDL) also increased significantly compared to the control group (P≤0.05). This study reveals that using 2% SBL and 3% CLA in rainbow trout feed can promote resistance to hypoxic stress

Histopathological effects of aflatoxin B1 and zearalenone on liver tissue of rainbow trout (Oncorhynchus mykiss)

The aim of this study was to evaluate the histological effects of aflatoxin B1 (AFB1) and zearalenone (ZEA) on the liver tissue of the rainbow trout. In this study, 540 rainbow trout 12.07±0.23 g (Mean±SD), as 9 experimental treatments with three replications were fed separately and simultaneously with diets containing different concentrations of AFB1 and ZEA over 60 days. In this regard, the concentrations of 50 and 100 ppb AFB1 and 300 and 600 ppb of ZEA were used. At the end of the experimental period, the liver tissue was sampled and pathological changes were qualitatively and semi-quantitatively examined. The toxin-induced histological damage included necrosis and deformation of hepatocytes. The severity of tissue lesions increased with increasing dietary levels of AFB1 and ZEA separately and simultaneously. The results showed that the severity of lesions was higher in fish receiving diets containing combinations of AFB1 and ZEA in comparison to other treatments

Synergistic toxicity of dietary aflatoxin B1 (AFB1) and zearalenone (ZEN) in rainbow trout (Oncorhynchus mykiss) is attenuated by anabolic effects

Although several studies have reported co-occurrence of mycotoxins in fish feed limited information is available on the physiological effects. In the current study, the single and combined effect of added dietary AFB1 and ZEN in various concentrations for 60 days was tested in rainbow trout on growth parameters, mortality, intestinal digestive enzymes activity and on serum and intestinal oxidative stress and immunological parameters and on intestinal histopathology, versus untreated controls. Both mycotoxins groups irrespective of concentration, showed a significant deterioration of SGR and FCR as compared to control, whereas no consistent differences in mortality were present. The small intestinal enzyme activity was significantly reduced by ZEN in particular at the higher mycotoxin concentrations and when combined with AFB1. Serum and intestinal immunological parameters were significantly affected largely consistent with additive and synergistic negative effects on the (innate) immune system, in particular enhanced inflammation. The latter was also reflected in the serum and intestinal oxidative stress parameters. Histopathological examination showed decreasing villus length and Goblet cell density with increasing mycotoxin load. It is concluded that the combination of AFB1 and ZEN clearly increased the toxic effect on the fish as far as the serum and intestinal parameters are concerned. This is in some cases merely additive, but clear synergistic toxicity was seen too, in particular at the higher mycotoxin concentrations. Surprisingly, the increasing intestinal impairment did not translate into increased growth retardation and mortality since those were similar in all non-control groups. This may be consistent with anabolic effects of mycotoxin (metabolites) as has been described before

Dietary aflatoxin B1 and zearalenone contamination affected growth performance, intestinal and hepatopancreas gene expression profiles and histology of the intestine and gill in goldfish, Carassius auratus

The effects of dietary aflatoxin B1 (AFB1) and/or zearalenone (ZEA) contamination on goldfish, was investigated. Total of 540 fingerlings, 6.25 ± 0.12 g, were randomly allocated to experimental groups comprised of factorial designation of different dietary AFB1 (0, 50 and 100 ppb) and ZEA (0, 500 and 1000 ppb) concentrations for 60 days. Each treatment was conducted in triplicate. Results showed dietary AFB1 and/or ZEA depressed the growth performance of fish; the highest and lowest weight gain (WG), final body weight, thermal growth coefficient (TGC) and daily growth coefficient (DGC) were observed in control group and AFB50ZEA1000, respectively (P < 0.05). Moreover, dietary AFB1 and/or ZEA significantly affected the gene expressions of Caspase 3, Cytochrome P450 (CYP) 1A1, Glutathione S-transferases (GST) and Heat shock proteins 70 (HSP70) in a dose-dependent and tissue specific manner (hepatopancreas or intestine) (P < 0.05). In the hepatopancreas, the highest relative expression of Caspase 3 (2.08 ± 0.43), CYP1A1 (2.73 ± 1.18), GST (32.86 ± 4.03) and HSP70 (7.55 ± 2.35) genes were observed in AFB100ZEA1000, AFB50ZEA0, AFB0ZEA1000 and AFB0ZEA1000 groups, respectively (P < 0.05). However, the highest relative expression of Caspase 3 (39.70 ± 10.98), CYP1A1 (966.4 ± 68.6), GST (175.8 ± 37.1) and HSP70 (1.01 ± 0.22) genes in the intestinal tissue were observed in AFB100ZEA1000, AFB0ZEA1000, AFB100ZEA500 AFB0ZEA0 groups (P < 0.05). The highest scores of the intestine tissue inflammation (4.0 ± 0.75) and necrosis (4.0 ± 0.75) were observed in AFB100ZEA500 group (P < 0.05). The results indicated the significant contribution of the intestine in metabolism/excretion of the feed-born toxins. Furthermore, the results revealed that dietary AFB1 and/or ZEA contamination could negatively affect fish performance and detoxifying genes expression profiles at concentrations even lower than those indicated in the literature as the safe feed mycotoxin thresholds