Effect of milk thistle (Silybum marianum) on the antioxidant status of laying hens under cadmium load

This study investigates the effect of cadmium exposure on the intensity of lipid peroxidation processes and the state of the antioxidant defense system in laying hens, as well as the efficacy of using milk thistle (Silybum marianum) as a corrective agent under these conditions. A total of 16 laying hens aged 78 weeks were selected for the experiment. The birds were divided into two groups: control and experimental. Both groups received cadmium sulfate in their drinking water at a dose of 4 mg/kg body weight. The experimental group additionally received milk thistle fruit with their feed at a dose of 2.0 g/kg of feed once daily for 30 days. It was found that cadmium sulfate administration led to a significant increase in the concentration of primary, intermediate, and final lipid peroxidation products, particularly lipid hydroperoxides, diene conjugates, and TBARS (thiobarbituric acid reactive substances). Concurrently, there was a decrease in the level of reduced glutathione, as well as in the activity of glutathione peroxidase, superoxide dismutase, and catalase, indicating the development of oxidative stress. Feeding milk thistle to laying hens contributed to the normalization of key biochemical markers of lipid peroxidation: the concentrations of lipid hydroperoxides, diene conjugates, and TBARS were significantly lower in the experimental group compared to the control on days 21 and 30 of the study. Additionally, there was a statistically significant increase in the level of reduced glutathione and in the activity of glutathione peroxidase, superoxide dismutase, and catalase, indicating enhanced systemic antioxidant defense. Thus, milk thistle demonstrates a pronounced protective effect on the antioxidant defense systems of the body under cadmium-induced stress, reduces the intensity of lipid peroxidation, and may be recommended as a natural remedy for the prevention and correction of toxic damage caused by heavy metals.