Nutritional risk factors for liver damage were surveyed in Black-Pied French dairy herds using serum glutamic dehydrogenase and gamma glutamyl transferase levels to monitor liver dysfunction.The 34 herds chosen were free of parasitic liver injuries. Feeding systems, nutritional blood parameters and production characteristics are analyzed. Two risk factors appeared to be involved in hepatic injury: feeding of fresh rape (Brassica napus) and high levels of serum urea (>/=6.64 mmol/L) associated with grass pasture or dietary nonprotein nitrogen with corn silage