Animal welfare, etológia és tartástechnológia Animal welfare, ethology and housing systems

The effect of medium dietary levels of Fusarium mycotoxins deoxynivalenol (DON) with or without zearalenone (ZEA) on the activity of glutathione peroxidase (GPx) in blood and tissues,thioredoxin reductase (TrxR) in liver tissue, superoxide dismutase (SOD) in erythrocytes, the activity of γ-glutamyltransferase (GGT) in plasma and concentrations of malondialdehyde (MDA)in liver and kidney was investigated on Ross 308 hybrid broiler chickens of both sexes. After hatching, all chickens were fed an identical control diet for two weeks. Then chickens of Group 1 fed a diet contaminated with DON (3 mg DON/kg), while Group 2 was fed a contaminated diet containing DON and ZEA, each at a level of 3.4 mg/kg. All contaminated diets were prepared in the laboratory using maize cultivated with Fusarium graminearum. Intake of contaminated diet with the combination of mycotoxins DON and ZEA resulted in significantly increased levels of MDA in liver and kidney tissues, while the activity of TrxR in liver and GPx in both tissues did not affected. On the other hand, feeding of diet contaminated with 3 mg DON/kg and only background ZEA level (0.15 mg/kg) reduced activity of GPx in liver only and increased level of MDA in liver and kidney tissue. The activity of blood GPx and SOD in erythrocytes did not affected by dietary mycotoxins. The activity of GGT in plasma was significantly elevated in all chickens fed contaminated diets. Presented results demonstrate that diet contaminated with DON and ZEA at medium dietary levels is already able to induce oxidative stress in broilers. Introduction Mycotoxins as secondary metabolites of several moulds differ in their chemical structure, toxic properties and biological effects. In the mild climatic zone, maize is usually infected by members of the genus Fusarium, especially by the species Fusarium graminearum. The most important mycotoxins produced by these moulds are DON, its acetylated derivatives, ZEA and nivalenol (Binder et al., 2007). Deoxynivalenol (DON) is a member of trichothecene mycotoxin group. The mode of toxic action of DON is inhibition of protein synthesis, thus affecting rapidly dividing cells, such as those of the gastrointestinal tract and the immune system (Sergent et al., 2006). ZEA is a naturally occurring non-steroidal mycotoxin with oestrogenic properties, which is known to induce functional and morphological alteration in reproductive organs due to the activation of estrogen receptors. In addition, ZEA has been shown to be hepatotoxic, haemotoxic, immunotoxic and genotoxic (Zinedine et al., 2007). Adverse effects of mycotoxins on cells are also associated with the increased production of free radicals and reactive oxygen species resulting in oxidative damage of target tissues (Dvorska et al., 2007). The aim of our studies was to investigate the effects of diets contaminated with DON and ZEA in complete feed on parameters of tissue oxidative stress and antioxidant status in fattening chickens. Material and methods Experimental design, diets and analysis One-day-old chickens of Ross 308 hybrid broilers of both sexes were randomly divided into dietary treatment groups and all were fed an identical uncontaminated starter diet for 2 weeks. After this time, control broilers continued to be fed the uncontaminated diet and chickens from experimental Group 1 being fed a diet contaminated with DON (3 mg DON/kg) and only background ZEA level (0.15 mg/kg). Group 2 was given a diet contaminated with DON and ZEA, each at a level of 3.4 mg/kg. Rearing of the chickens was done with a lighting regimen of 23 h light to 1 h dark and lasted for four