Abstract
Our previous study was intended to estimate the grazing intake of steers on the native pasture by chromogen-chromic oxide method. The results of the study showed that the recovery rate of chromogen was abnormally low in autumn in spite of the satisfactory rate in spring and that the estimation of grazing intake on the native pasture in autumn by this method was therefore practically impossible. Thus it was assumed that the low recovery rate of chromogen might be attributed to the leaf senescence of the native grass grazed in autumn. In this study, therefore, the recovery rates of chromogen were measured using sheep fed on Miscanthus sinensis of different growth stage through the seasons in 1976 and 1978. The results obtained were as follows: The concentration of chromogen and its recovery rate were satisfactory for each grass fed in spring and summer. As for the grass fed in autumn, the concentration in 1978 and the recovery rate in 1976 were extremely low. From this results it was presumed that the chromogenic substances in autumn grass became unstable at first and then decreased later according to the stage of aging. Namely autumn grass fed in 1978 reached such a late stage that the most of chromogenic substances had disappeared, whereas the one fed in 1976 still remained in an early stage and preserved the unstable chromogenic substances which might be decomposed and absorbed while passing through the digestive organ of animal.
