Identification of the phenolic substances in bovine urine associated with oak leaf poisoning.

Six phenolic substances in bovine urine associated with oak leaf poisoning were identified by means of the ferric chloride reaction, paper chromatography and gas-liquid chromatography. The results indicate that these are neither oak tannin nor tannic acid but small molecular weight phenolic compounds. The concentration of free volatile phenols in the urine of cattle affected by oak leaves (n = 9, 26.57 +/- 11.20 mg litre-1) was significantly higher than in normal cattle (n = 9, 2.59 +/- 0.03 mg litre-1).