Abstract
In order to obtain some information on the cycling of minerals in grasslands, composition and recovery of minerals in the excreta of adult dairy cattle (Holstein cows) were determined on the materials collected from the digestibility trials in stalls. Particular attention was given to the relationship between minerals in grasses and those in faeces. In the first experiment, materials were collected from dry cows in June, August and October, 1971. Minerals such as iron, manganese, copper and zinc were recovered in distinctly high amounts in the faeces collected in August. In the second experiment in July and October, 1972, composition and recoveries of minerals in the faeces, urine and milk were compared betwen dry and lactating cows. Calcium and phoshorus contents in the faeces and chlorine content in the urine from lactaing cows were lower than those from dry cows. The mineral contents in the urine varied among individual cows. In July, the total amount of iron in the faeces, urine and milk still had a trend of being recovered more than 100 per cent. It was also observed that potassium recovery in October was higher than that in July, and that its higher recovery was found mainly in the urine. Mineral components both from grasses and faeces were compared. Contents of such major faecal minerals with more than 80 per cent recovery as phosphorus, calcium and magnesium were 1.9 times as much as those of grasses. Contents of faecal trace elements with 100 per cent or more recovery, however, were 2.3 times as much as those of grasses.
