The effect of different label and processing methods of milk thistle on growth performance in broiler rabbits (HYLA, n = 255) fed with different concentration of milk thistle (Silybum marianum) was studied. Four experiments were conducted. Rabbits were fed with different concentrations of 1% non-fermented milk thistle (experimental group E1) and 0.5% fermented milk thistle (experimental group E2), and the results were compared with a control group C (standard feed ration without any supplementation). Each experiment started at 42 days of rabbits’ age and finished at 85 days of age. Observed parameters were: average daily gain, average daily feed consumption, total feed consumption, slaughter live weight, and carcass weight. The best results were showed in experimental group E2 (supplement of 0.5% fermented milk thistle). Significant differences (P