Abstract
The cause of grasstetany incidence of grazing cattle was investigated on Sotoyama pasture in Iwate-pref. where the first outbreak of the disease was reported in Japan, in relation to organic acid components in grass. Samples of orchardgrass were taken from two types of swards used for grazing and cut in May, August and October, 1974, respectively. Analyses of organic acids were made for the samples by programmed temperature gas chromatography. The results obtained were as follows ; 1) The contents of malic and quinic acids in orchardgrass were considerably higher than those of other acids in most cases of sampling. 2) Orchardgrass did not show any significant trend concerning with contents of citric and t-aconitic acid which have been considered to be closely related to outbreak of the disease. The content of citric acid was rather low and showed little change between seasons, although incidence of the disease has appeared mostly in spring at Sotoyama pasture. Moreover, t-aconitic acid was not detected in any samples. 3) Seasonal changes of total organic acid and malic acid coincided with occurrence of grasstetany. Further investigation, however, should be done on this point.
