Carbon isotope ratios of endogenous steroids in Belgian Blue and Holstein cattle: Method development, reference population studies and application to steroid misuse control.

This first comprehensive investigation on the CIRs of endogenous urinary steroids demonstrated once more the potential of isotope ratios in aiding discrimination between endogenously produced and exogenously administered steroids. By means of the reference population-derived CIRs, it is possible to apply cattle-specific thresholds to differentiate between treated and non-treated animals.