Rabbits are an important source of high-quality dietary proteins. Intensive farming is connected with the protection of rabbits against diseases, mainly digestive disorders. Previously used antibiotics have been replaced with other types of compounds with prophylactic or curative effects, substances or mixtures of natural origin are preferred. Mechanically processed Silybum marianum fruits − 0.2% or 1% (w/w), were added to the standard diet of HYLA broiler rabbits in a 42-day fattening experiment repeated in quadruplet. At the end of the experiment, the main compounds of interest − selected flavonolignans and taxifolin, were subject of HPLC/MS analyses in feed, plasma, urine and faeces. Data showed a mild effect on the growth performance of rabbits (carcass weight and carcass yield in the group fed 1% mechanically processed S. marianum fruits), but no effect on the majority of selected blood biochemical parameters and markers of oxidative stress after the application of the feed containing S. marianum constituents. However, when in one repetition a higher incidence of health problems connected with digestive disorders occurred, the diet containing the highest content of S. marianum constituents was able to attenuate the morbidity and mortality of rabbits. The addition of phytopreparations based on S. marianum constituents to the animal diet is promising for conventional methods of rabbits farming.