Although polychlorinated biphenyls (PCBs) have been banned worldwide in 2004 by the Stockholm Convention on Persistent Organic Pollutants (POPs), it is estimated that around 80% of the total PCB amount produced still remains in our environment1,2. Characterized by their easily disperse, highly lipophilic and poorly degradable properties, PCBs are highly persistent and bioaccumulate into the animal food chain. Thus, consumption of food of animal origin embodies the main PCB exposure route for humans, accounting for more than 90% of the overall human exposure3. Therefore, it is important to understand the transfer of such compounds in the food chain, in order to ensure the chemical safety of animal products and further reduce the human exposure. In livestock, the fate of POPs is primarily investigated via feeding experiments, from which the biotransfer factor (BTF), the bioconcentration factor (BCF) or the assimilation efficiency (AE) can be derived for meat producing animals. Such transfer parameters are widely used in order to assess and manage the chemical risk in animal farming systems. Nonetheless, data for PCBs in meat producing growing cattle are scarce, since the few studies with beef animals focus mainly on polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), where no transfer rates were calculated4,5. Additionally, some studies in monogastrics highlight the dependency of BTF and BCF on animal physiology, especially on body lipid dynamics influenced by growing rate6,7. The aim of the present study was to better understand the transfer of PCBs in growing cattle depending on animal physiology. It was hypothesized that body fatness and growing rate will affect the transfer factors (BTF, BCF and AE).