Ammoniated forage poisoning of cattle

Cattle fed ammoniated roughages have developed a syndrome of hyperexcitability, such as bovine bonkers and crazy syndrome, in several countries. Toxins which cause the poisoning appear to be formed by chemical reaction during ammoniation of roughages with high sugar content. Such toxins have not been fully specified yet, but conventionally one of such causative toxins is considered to be 4-methylimidazole (4MI) yielded upon the chemical reaction between sugar and ammonia. In this paper, incidence of the poisoning of cattle in foreign countries have been reviewed, and as a part of studies to clarify lesions and onset mechanisms of these intoxication, clinico-biochemical and physiological conditions of poisoning calves taking milk from cows fed on ammoniated hay (test milk) were compared with those of calves taking milk added with 4MI (4MI group). Following the administration of the test milk, clinical symptoms, electrocardiographic findings and auditory brainstem response (ABR) were examined and blood was collected to assay blood components. Two neonatal administred test milk exhibited fever and abnormal behavior, such as hyperexcitation and rotatory movement, two days after the first administration. ABR decreased and disappeared intermittently during these period. Of the 6 calves taking the milk added 200-300mg of 4MI, 4 calves after birth 2 hours to 2 days old showed similar symptoms and ABR with test milk group. However, 2 calves after birth 6 and 12 days old showed no fever, rotatory movement and abnormal ABR. In almost all experimental cattle, lactic acid and pyruvic acid concentrations in blood elevated at the time onset. No remarkable changes in another blood components were except for these substances. It was clarified that an excessive supply of the ammoniated hay to cow caused some central nervous disorders in newborn calves through the milk, and the symptoms resembled those of newborn calves taking milk added high dosage of 4 MI